PATENT DOCUMENT

Publication Number: US-8957577-B2
Application Number: US-201113251108-A
Country: US
Kind Code: B2

Title: Integrated thermal spreading

Abstract:
Techniques are provided for removing thermal gradients from an organic light emitting diode (OLED) display. In one embodiment, an OLED display device includes a thermally conductive layer placed between electronic components housed within the device and the OLED display. Heat given off by the electronic components is transferred from warm to cold regions of the thermally conductive layer to create a more uniform ambient temperature across the back of the OLED display. Some embodiments indicate a position of the thermally conductive layer within layers of an OLED display stack (e.g., between a glass substrate and polyimide layer). Some embodiments include a specific range of thermal conductivities and/or thicknesses desired for the thermally conductive layer.

Claims:
What is claimed is: 
     
       1. An organic light emitting diode (OLED) display device comprising:
 an OLED display panel; 
 a thermally conductive layer disposed adjacent the OLED display panel, wherein the thermally conductive layer has a thickness of approximately 20 microns to 500 microns and is configured to transfer heat from a relatively higher temperature region of the OLED display panel to a relatively lower temperature region of the OLED display panel; and 
 a substrate, wherein the thermally conductive layer is disposed over the substrate and wherein the OLED display panel is disposed over the thermally conductive layer. 
 
     
     
       2. The display device of  claim 1 , wherein the display device comprises different components which generate different amounts of heat. 
     
     
       3. The display device of  claim 2 , wherein the different components comprise electronic components disposed within the display device adjacent the thermally conductive layer opposite the OLED display panel. 
     
     
       4. The display device of  claim 2 , wherein the different components comprise a processor, GPU, transmitter, battery, display driver, or any combination thereof. 
     
     
       5. The display device of  claim 2 , wherein the different amounts of heat generated by the different components varies with respect to time. 
     
     
       6. The display device of  claim 1 , wherein the thermally conductive layer has a thermal conductivity of approximately 200 W/mK to 8000 W/mK. 
     
     
       7. The display device of  claim 1 , comprising a plurality of layers disposed adjacent the OLED display panel in addition to the thermally conductive layer. 
     
     
       8. A method of operating an organic light emitting diode (OLED) display device, comprising:
 generating heat in the display device adjacent an OLED display panel; and 
 spreading the heat across the OLED display panel with a thermally conductive layer disposed between a glass display substrate and a light emitting diode layer, wherein the light emitting diode layer emits light away from the glass display substrate. 
 
     
     
       9. The method of  claim 8 , wherein the generating heat comprises generating heat from a processor, GPU, transmitter, battery, display driver, or any combination thereof. 
     
     
       10. The method of  claim 8 , wherein the spreading the heat across the OLED display panel comprises transferring heat from a relatively higher temperature region of the OLED display panel to a relatively lower temperature region of the OLED display panel. 
     
     
       11. An electronic device display, comprising:
 a polymer layer; 
 an organic light emitting layer on the polymer layer; 
 a glass substrate; and 
 a thermally conductive layer interposed between the glass substrate and the organic light emitting diode layer, wherein the thermally conductive layer transfers heat between regions of the electronic device display. 
 
     
     
       12. The electronic device display defined in  claim 11  wherein the polymer layer comprises:
 a polyimide layer that prevents current flow between the light emitting diode layer and the thermally conductive layer. 
 
     
     
       13. The electronic device display defined in  claim 11  wherein the thermally conductive layer is directly adjacent to the glass substrate. 
     
     
       14. The electronic device display defined in  claim 11  wherein the thermally conductive layer comprises at least one thermally conductive material selected from the group consisting of: copper, graphite, graphene, carbon nanotubes, aluminum, gold, and silver.

Description:
BACKGROUND 
     The present disclosure relates generally to electronic display devices and more specifically to controlling thermal spreading in electronic display devices. 
     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. 
     Organic light emitting diodes (OLEDs) are being increasingly employed for display applications in a wide variety of electronic devices, including such consumer electronics as televisions, computers, and handheld devices (e.g., cellular telephones, digital cameras, audio and video players, gaming systems, and so forth). Such OLED devices typically include a flat display panel having, among other things, an array of OLEDs that emit light to form an image. Each OLED includes one or more thin organic layers disposed between two charged electrodes (anode and cathode). The organic layers may include, for example, a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, and an electron injection layer. Upon application of an appropriate voltage to the OLED device, the injected positive and negative charges recombine in the emissive layer to produce light. 
     The luminance available from these organic layers generally degrades throughout the lifetime of the OLED. The lifetime of OLEDs used in electronic device displays may be affected by their temperature. For example, the OLED may work less efficiently at lower temperatures, requiring a slightly higher applied voltage to emit a desired amount of light, and OLED luminance generally degrades faster when the OLED is driven harder. Moreover, frequently used electronic components within an OLED device may produce excess heat, leading to high temperature concentrations in regions adjacent the OLED display. For example, a cellular phone user who engages in frequent telephone conversations may use the transmitter positioned near an upper region of the display, while a user who plays more video games may use the processor positioned near a lower region of the display. The OLEDs may degrade even faster in regions of the display exposed to these higher temperatures, resulting in non-uniform visual artifacts in the displayed image. In particular, white spots or image burn-in may result from temperature gradients within the display. 
     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. 
     In one embodiment, an organic light emitting diode (OLED) display device is provided. The display device includes an OLED display panel and a thermally conductive layer disposed adjacent the display panel. The thermally conductive layer facilitates heat transfer from high temperature to low temperature regions of the OLED display panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a block diagram of an electronic device, in accordance with aspects of the present disclosure; 
         FIG. 2  is a perspective view of a computer in accordance with aspects of the present disclosure; 
         FIG. 3  is a front view of a handheld electronic device in accordance with aspects of the present disclosure; 
         FIG. 4  is a cross-sectional side view of an organic light emitting diode (OLED) stack, in accordance with aspects of the present disclosure; 
         FIG. 5  is a top view of thermal gradients across a substrate of a handheld device, in accordance with aspects of the present disclosure; 
         FIG. 6  is a side view of a display stack, including the OLED stack of  FIG. 4 , in accordance with aspects of the present disclosure; 
         FIG. 7  is a side view of another arrangement of a display stack, including the OLED stack of  FIG. 4 , in accordance with aspects of the present disclosure; and 
         FIG. 8  is a top view of thermal spreading in a display due to a thermally conductive layer of the handheld device of  FIG. 5 , 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. 
     Organic materials are becoming increasingly utilized in display technology due to the low cost and high performance offered by organic electronic devices. However, typical organic light emitting diode (OLED) display devices may experience uneven degradation of certain regions of the display due to thermal gradient regions caused by the operation of certain electronic components within the device. One or more embodiments of the present disclosure spreads heat given off by the electronic components through a thermally conductive layer placed between the electronics and the OLED display. 
     With these foregoing features in mind, a general description of suitable electronic devices for implementing aspects of the present techniques is provided. In  FIG. 1 , a block diagram depicting various components that may be present in electronic devices suitable for use with the present techniques is provided. In  FIG. 2 , one example of a suitable electronic device, here provided as a computer system, is depicted. In  FIG. 3 , another example of a suitable electronic device, here provided as a handheld electronic device, is depicted. These types of electronic devices, and other electronic devices featuring OLED displays, may be used in conjunction with the present techniques. For example, these and similar types of electronic devices may utilize a thermally conductive material layer to facilitate heat spreading in accordance with aspects of the present disclosure. 
     As may be appreciated, electronic devices may include various internal and/or external components which contribute to the function of the device. For instance,  FIG. 1  is a block diagram illustrating components that may be present in one such electronic device  10 . Those of ordinary skill in the art will appreciate that the various functional blocks shown in  FIG. 1  may include hardware elements (including circuitry), software elements (including computer code stored on a computer-readable medium, such as a hard drive or system memory), or a combination of both hardware and software elements.  FIG. 1  is only one example of a particular implementation and is merely intended to illustrate the types of components that may be present in the electronic device  10 . For example, in the presently illustrated embodiment, these components may include a display  12 , input/output (I/O) ports  14 , input structures  16 , one or more processors  18 , one or more memory devices  20 , non-volatile storage  22 , graphics processing unit (GPU)  24 , cellular transmitter (RF circuitry)  26 , and suitable power source (battery)  28 . 
     The display  12  may be used to display various images generated by the electronic device  10 . The display  12  may be any suitable display, such as an OLED display. Additionally, in certain embodiments of the electronic device  10 , the display  12  may be provided in conjunction with a touch-sensitive element, such as a touchscreen, that may be used as part of the control interface for the device  10 . The display  12  may include a stack of materials and organic compounds deposited in layers onto a substrate, wherein a thermally conductive layer is configured to remove thermal gradients within the display  12 . 
     Processors  18  may provide the processing capability to execute the operating system, programs, user and application interfaces, and any other functions of the electronic device  10 . The processors  18  may include one or more microprocessors, such as one or more “general-purpose” microprocessors, one or more special-purpose microprocessors or ASICS, or some combination of such processing components. For example, the processors  18  may include one or more reduced instruction set (RISC) processors, as well as video processors, audio processors, and the like. As will be appreciated, the processors  18  may be communicatively coupled to one or more data buses or chipsets for transferring data and instructions between various components of the electronic device  10 . For example, one or more display drivers may aid in transferring display data from the processors  18  to the display  12 . 
     Programs or instructions executed by processor(s)  18  may be stored in any suitable manufacture that includes one or more tangible, computer-readable media at least collectively storing the executed instructions or routines, such as, but not limited to, the memory devices and storage devices described below. Also, these programs (e.g., an operating system) encoded on such a computer program product may also include instructions that may be executed by the processors  18  to enable the device  10  to provide various functionalities. 
     The instructions or data to be processed by the one or more processors  18  may be stored in a computer-readable medium, such as a memory  20 . The memory  20  may include a volatile memory, such as random access memory (RAM), and/or a non-volatile memory, such as read-only memory (ROM). The memory  20  may store a variety of information and may be used for various purposes. For example, the memory  20  may store firmware for electronic device  10  (such as basic input/output system (BIOS)), an operating system, and various other programs, applications, or routines that may be executed on electronic device  10 . In addition, the memory  20  may be used for buffering or caching during operation of the electronic device  10 . 
     The components of the device  10  may further include other forms of computer-readable media, such as non-volatile storage  22  for persistent storage of data and/or instructions. Non-volatile storage  22  may include, for example, flash memory, a hard drive, or any other optical, magnetic, and/or solid-state storage media. Non-volatile storage  22  may be used to store firmware, data files, software programs, wireless connection information, and any other suitable data. 
     In addition, the device  10  may include a GPU  24 , which configures complicated visual data to be shown on the display  12 , such as when playing games, videos, and the like. Data may be transmitted out of the device via RF circuitry  26  (e.g., voice data sent through a cellular transmitter of a mobile telephone). A rechargeable battery  28  may supply power to the processors  18  and other components of the device  10 . Hardware components such as the GPU  24 , RF circuitry  26 , and battery  28  may produce heat when operated heavily or continually, and depending on the form of the device  10 , these components may be located near the display  12 . 
     The electronic device  10  may take the form of a computer system or some other type of electronic device. Such computers may include computers that are generally portable (such as laptop, notebook, tablet, and handheld computers), as well as computers that are generally used in one place (such as conventional desktop computers, workstations and/or servers). In certain embodiments, electronic device  10  in the form of a computer may include a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. of Cupertino, Calif. By way of example, an electronic device  10  in the form of a laptop computer  30  is illustrated in  FIG. 2  in accordance with one embodiment. The depicted computer  30  includes a housing  32 , a display  12  (e.g., in the form of an OLED display  34  or some other suitable display), I/O ports  14 , and input structures  16 . One or more display drivers (not shown), disposed in the housing  32  adjacent the display  12 , may produce heat near regions of the OLED display  34  where the OLEDs are driven harder. 
     The display  12  may be integrated with the computer  30  (e.g., such as the display of the depicted laptop computer) or may be a standalone display that interfaces with the computer  30  using one of the I/O ports  14 , such as via a DisplayPort, Digital Visual Interface (DVI), High-Definition Multimedia Interface (HDMI), or analog (D-sub) interface. For instance, in certain embodiments, such a standalone display  12  may be a model of an Apple Cinema Display®, available from Apple Inc. 
     Although an electronic device  10  is depicted in the context of a computer in  FIG. 2 , an electronic device  10  may also take the form of other types of electronic devices. In some embodiments, various electronic devices  10  may include mobile telephones, media players, personal data organizers, handheld game platforms, cameras, and combinations of such devices. For instance, as generally depicted in  FIG. 3 , the device  10  may be provided in the form of handheld electronic device  36  that includes various functionalities (such as the ability to take pictures, make telephone calls, access the Internet, communicate via email, record audio and video, listen to music, play games, and connect to wireless networks). By way of further example, handheld device  36  may be a model of an iPod®, iPod® Touch, or iPhone® available from Apple Inc. In the depicted embodiment, the handheld device  36  includes the display  12 , which may be in the form of an OLED display  34 . The OLED display  34  may display various images generated by the handheld device  36 , such as a graphical user interface (GUI)  38  having one or more icons  40 . 
     In another embodiment, the electronic device  10  may also be provided in the form of a portable multi-function tablet computing device (not illustrated). In certain embodiments, the tablet computing device may provide the functionality of two or more of a media player, a web browser, a cellular phone, a gaming platform, a personal data organizer, and so forth. By way of example only, the tablet computing device may be a model of an iPad® tablet computer, available from Apple Inc. 
     With the foregoing discussion in mind, it may be appreciated that an electronic device  10  in either the form of a computer  30  ( FIG. 2 ) or a handheld device  36  ( FIG. 3 ) may be provided with a display  12  in the form of an OLED display  34 . As discussed above, an OLED display  34  may be utilized for displaying respective operating system and/or application graphical user interfaces running on the electronic device  10  and/or for displaying various data files, including textual, image, video data, or any other type of visual output data that may be associated with the operation of the electronic device  10 . 
     An OLED display  34  outputs visual data through an array of OLED devices arranged side by side on a flat panel or substrate. A cross-sectional side view of a portion of an OLED device for use in an electronic device  10  with OLED display  34  is illustrated in  FIG. 4 . The portion of the OLED device, also referred to as the OLED stack  42 , may include a top electrode (i.e., cathode)  44  and a bottom electrode (i.e., anode)  46 , with organic layers  48  disposed between the cathode  44  and the anode  46 . In some embodiments, the organic layers  48  may include a hole injection layer  50  which may be disposed over the anode  46 . A hole transport layer  52  may be disposed over the hole injection layer  50 , and an emissive layer  54  may be disposed over the hole transport layer  52 . An electron transport layer  56  may be disposed over the emissive layer  54 , and an electron injection layer  58  may be disposed over the electron transport layer  56 . 
     During operation of the electronic device  10  with OLED display  34 , a voltage may be applied across the OLED stack  42 . The voltage may charge the anode  46  to a positive charge and the cathode  44  to a negative charge, and electrons may flow through the stack  42  from the negatively charged cathode  44  to the positively charged anode  46 . More specifically, electrons may be withdrawn from the organic materials adjacent to the anode  46  and injected to the organic materials adjacent to the cathode  44 . The process of withdrawing electrons from the anode-side organic materials may also be referred to as hole injection and hole transport, and the process of injecting the electrons to the cathode-side organic materials may also be referred to as electron transport and electron injection. During the process of hole and electron transport/injection, electrons are withdrawn from the hole injection layer  50 , transported through the hole transport layer  52  and the electron transport layer  56 , and injected to the electron injection layer  58 . Electrostatic forces may combine the electrons and holes in the emissive layer  54  to form an excited bound state which upon de-excitation, emits radiation having frequencies in the visible region of the electromagnetic spectrum (e.g., visible light). The frequency of the emitted radiation and the colors and/or characteristics of visible light may vary in different embodiments depending on the properties of the particular materials used in the OLED stack  42 . 
     An OLED display  34  generally includes a plurality of OLED stacks  42  arranged as a matrix and deposited on a substrate, and may include additional layers positioned above and/or below the OLED stack  42 . Over time and with use, the organic layers  48  may break down, causing the luminance emitted from the OLED stack  42  to degrade. This degradation process typically occurs at a faster rate for OLEDs exposed to higher temperatures due to higher driving voltages and/or ambient temperatures. For example, temperature gradients across an OLED display  34 , over an extended period of time, may cause increased degradation of the OLED display  34  in high temperature regions. The accelerated loss of luminance may cause these regions to emit light at an undesired brightness and/or color, and such regions may be visually manifested as permanent white or yellow spots in the image on the OLED display  34 . 
     High temperatures caused by operation of the OLED display  34  itself may also lead to temperature gradients across the OLED display  34 . Some OLEDs may be driven more frequently and/or at higher voltages than other OLEDs. For example, a display  34  may show an image of a clock in a region of the display, and the clock image may feature a number of white pixels. White pixels on an OLED display  34  may require higher voltages across a number of OLEDs than the voltages required to produce other colored pixels. Therefore, images and icons, especially white ones, shown on regions of an OLED display  34  for an extended period of time may cause the OLED pixels to heat up in those regions. This heat may lead to temperature gradients across an OLED display  34 , and, consequently, accelerated degradation of the OLED display  34 . 
     Furthermore, heat given off by electronic components, especially the processor  18  and the RF circuitry  26 , within the device  10  may transfer to local regions of the display  34 , forming thermal gradient regions on the display  34 .  FIG. 5  illustrates a distribution of thermal gradient regions  64  that may exist on an OLED display  34  within a handheld device  36 . It should be noted that  FIG. 5  is meant to illustrate one possible layout of electronic components beneath the OLED display  34  of the handheld device  36 , and many other layouts are possible. 
     As illustrated in  FIG. 5 , four temperature gradient regions  64   a ,  64   b ,  64   c , and  64   d  are represented on the display  34 , each corresponding to a different electronic component that may be housed within the handheld device  36 . Such electronic components may include the GPU  24 , RF circuitry  26 , microprocessor  18 , and battery  28 . These, among others, are relatively large electronic components within the handheld device  36  that may produce heat when operated for an extended period of time. For example, the battery  28  may heat up while the electronic device  10  is receiving charge, the RF circuitry  26  of a portable telephone may heat up during a lengthy telephone call, the GPU  24  may heat up as a graphically complicated game or video is displayed on the electronic device  10 , and the microprocessor  18  may heat up while the device is used heavily to process information. 
     The different electronic components may produce heat at different temperatures, which may result in differentially affecting the temperatures at each of the thermal gradient regions  64  across the display  34 . The different temperatures which affect these thermal gradient regions  64  may also change over time as certain electronic components are used more or less often. In addition, it is possible that not all major electronic components housed within the handheld device  36  may be operating simultaneously or in a manner which produces a steady state thermal gradient profile. For example, a user may play games with complicated graphics on the handheld device without transmitting data out of the device, in which case thermal gradient regions  64   a  and  64   c  may form on the display  34  over regions of the display  34  which are adjacent to the GPU  24  and microprocessor  18 , but not over regions of the display  34  adjacent to the RF circuitry  26 . Thermal gradient regions  64  across the display  34  may also be affected by the placement of the electronic components within the handheld device  36 , as certain components may be located closer to or further from the display  34  plane. 
     To prevent temperature gradient regions  64  in the display  34  from causing uneven image degradation of the OLED display  34  (e.g., white spots), a layer of material with high thermal conductivity may be deposited between heat-producing components and the OLED stacks  42 . As illustrated in  FIG. 6 , a thermally conductive layer  76  may form one layer of an OLED display stack  78 . The OLED display  34  of an electronic device  10  may feature all the layers shown in the display stack  78 , which may be continuous layers extending over the entire display area and disposed above or below an array of OLED stacks  42 . The display stack  78  may include, for example, a substrate  62 , conductive layer  76 , polyimide layer  80 , OLED stack  42 , and any additional protective layers such as thin film encapsulation layer  82 . 
     Structural support of the display stack  78  is provided by the substrate  62 , on which subsequent layers may be disposed. The substrate  62 , which may be glass, separates other layers of the display stack  78  from the internal components of the electronic device  10 . The polyimide layer  80  may act as an electrical insulator between the OLED stack  42  and the thermally conductive layer  76 , preventing current that flows into the OLED stack  42  from flowing into other components of the display stack  78  through the thermally conductive layer  76 . The thin film encapsulation  82  may be disposed above the OLED stack  42  to form a translucent boundary over the OLED stack  42 , allowing light emitted from the OLED stack  42  to pass through and form an image on the OLED display  34 . 
     A material with thermal conductivity within the range of approximately 200 Watts per meter Kelvin (W/mK) to 8000 W/mK may be appropriate for the thermally conductive layer  76 . Some suitable materials for the thermally conductive layer  76  include copper (400 W/mK), graphite (240 W/mK), graphene (4800-5300 W/mK), carbon nanotubes (3500 W/mK), aluminum (237 W/mK), gold (318 W/mK) and silver (429 W/mK). In some embodiments, the thermally conductive layer  76  may have a thickness ranging from approximately 20 microns to 500 microns. 
     Some OLED displays  34  include an optically opaque layer on the back surface. This layer could be paint, PVD, or black-colored polyimide or PET. This is a functional layer, meant to absorb ambient light that passes through the display, improving contrast. However, the thermal conductivity of PET is approximately 0.2 W/mK, which is not high enough to distribute heat across the layer and eliminate thermal gradient regions  64 . Thus, in some embodiments, a conductive layer  76  may replace, or be added to, a PET layer within the display stack  78 , in order to improve heat spreading across the area beneath an array of OLED stacks  42 . 
     A discussed above, the thermally conductive layer  76  may be disposed between the substrate  62  and polyimide layer  80 , as shown in the illustrated embodiment, or beneath the substrate  62 , between electronic components housed within the device and the substrate  62 . Other arrangements or additions of layers within the display stack  78  may also be possible, as will be appreciated by those skilled in the art. For example, in some embodiments, the thermally conductive layer  76  may be disposed beneath the substrate  62 , as illustrated in  FIG. 7 . In addition, a variety of thermally conductive materials may be appropriate for the thermally conductive layer  76  in OLED displays  34  for different electronic device  10  applications. That is, certain conductive materials may be better suited for certain OLED displays  34 , depending on the location and expected heat generation of electronic components of the system located beneath the OLED display  34 . 
     Heat from thermal gradient regions  64  across the display  34  may spread throughout the thermally conductive layer  76  to create a more uniform temperature distribution across the OLEDs in a device display  12 .  FIG. 8  illustrates the result of integrated thermal spreading that may occur in a conductive layer  76  of the handheld device  36  introduced in  FIG. 5 . The rectangles with dashed outlines indicate the layout of the electronic components located beneath the OLED display  34 . As represented by the diagonal lines across the display area, the thermally conductive layer  76  may facilitate the distribution of temperature across the plane of the OLED display  34 . Heat may enter the bottom of the thermally conductive layer  76  in concentrated regions as indicated by the thermal gradient regions  64  in the substrate  62  of  FIG. 5 . The high thermal conductivity of the thermally conductive layer  76  facilitates transfer of the incoming heat from relatively high temperature regions to lower temperature regions, spreading the heat throughout the thermally conductive layer  76 . At the top of the thermally conductive layer  76 , heat from the electronic components may enter the remaining layers of the OLED display  34  relatively uniformly across the display area. Thus, in accordance with the present techniques, the OLEDs may degrade more uniformly with time and use, preventing white spots and image burn-in from occurring at positions adjacent to heavily used electronic components. 
     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: 20110930
Publication Date: 20150217
Grant Date: 20150217
Priority Date: 20110930
Inventors: LYNCH STEPHEN BRIAN
ROTHKOPF FLETCHER R.
MYERS SCOTT ANDREW
Assignee: APPLE INC
CPC Classifications: [{"code": "H01L51/529", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/203", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49002", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/203", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49002", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K50/87", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/203", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K59/8794", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 47003278