PATENT DOCUMENT

Publication Number: US-12073782-B2
Application Number: US-202318335114-A
Country: US
Kind Code: B2

Title: Direct led temperature sensing systems and methods

Abstract:
A device may include an electronic display to display an image frame based on image data. The electronic display may include an illuminator that generates light, multiple light regulators that control emission of the light pixel locations on the electronic display based on bitplane data, and driving circuitry that applies an operating electrical stimulus to the illuminator during an emission period of the image frame and a reference electrical stimulus to the illuminator during an off period of the image frame. While the reference electrical stimulus is applied the bitplane data may be indicative of off bitplane. Additionally, the electronic display may include measurement circuitry that measures a response characteristic of the illuminator in response to the reference electrical stimulus and generates temperature data indicative of the temperature of the illuminator based on the response characteristic.

Claims:
What is claimed is: 
     
       1. A device comprising an electronic display configured to display an image frame based on image data, wherein the electronic display comprises:
 an illuminator configured to generate a light; 
 a plurality of light regulators configured to control emission of the light at a plurality of pixel locations of the electronic display based on bitplane data; 
 driving circuitry configured to apply an operating electrical stimulus to the illuminator during an emission period of the image frame and a reference electrical stimulus during an off period of the image frame, wherein the bitplane data comprises an off bitplane while the reference electrical stimulus is applied; and 
 measurement circuitry configured to measure a response characteristic of the illuminator in response to the reference electrical stimulus. 
 
     
     
       2. The device of  claim 1 , comprising control circuitry configured to adjust a parameter of operation of the electronic display based on the response characteristic. 
     
     
       3. The device of  claim 2 , wherein the measurement circuitry is configured to generate temperature data indicative of a temperature of the illuminator based on the response characteristic, and wherein the control circuitry is configured to adjust the parameter of operation based on the temperature data. 
     
     
       4. The device of  claim 2 , wherein the parameter of operation comprises the operating electrical stimulus, and wherein the operating electrical stimulus comprises an operating voltage or an operating current. 
     
     
       5. The device of  claim 2 , wherein the parameter of operation comprises the image data. 
     
     
       6. The device of  claim 1 , wherein the reference electrical stimulus comprises a reference current, and wherein the response characteristic comprises a voltage response. 
     
     
       7. The device of  claim 1 , wherein the illuminator comprises a light emitting diode (LED). 
     
     
       8. The device of  claim 1 , wherein, in response to the off bitplane, the plurality of light regulators are configured to direct the light to one or more light attenuators instead of the plurality of pixel locations. 
     
     
       9. The device of  claim 1 , wherein the electronic display comprises a reflective technology display. 
     
     
       10. The device of  claim 9 , wherein the plurality of light regulators comprises a plurality of mirrors, each associated with a respective pixel location of the plurality of pixel locations. 
     
     
       11. A method comprising:
 supplying a first electrical stimulus to an illuminator of an electronic display during an image frame; 
 operating a plurality of light regulators according to one or more bitplanes while supplying the first electrical stimulus to the illuminator, wherein the one or more bitplanes are associated with image data of the image frame; 
 supplying a second electrical stimulus to the illuminator during the image frame; 
 operating the plurality of light regulators according to an off bitplane while supplying the second electrical stimulus to the illuminator; 
 measuring an electrical response of the illuminator while supplying the second electrical stimulus to the illuminator; and 
 generating temperature data indicative of a temperature of the illuminator based on the electrical response. 
 
     
     
       12. The method of  claim 11 , wherein operating the plurality of light regulators according to the off bitplane comprises directing light generated by the illuminator in response to the second electrical stimulus to one or more light attenuators. 
     
     
       13. The method of  claim 11 , comprising supplying a third electrical stimulus to the illuminator during a second image frame subsequent to the image frame, wherein the third electrical stimulus is based on the temperature data. 
     
     
       14. The method of  claim 11 , wherein the electrical response of the illuminator comprises a forward voltage response to a reference current of the second electrical stimulus. 
     
     
       15. The method of  claim 11 , wherein the illuminator comprises a light emitting diode (LED) and the plurality of light regulators comprises a respective plurality of mirrors or a respective plurality of transmissivity regulating pixels. 
     
     
       16. An electronic display comprising:
 a first light emitting diode (LED) configured to emit a first light at a first color; 
 a second LED configured to emit a second light a second color different from the first color; 
 LED driving circuitry configured to apply:
 a first operating electrical stimulus to the first LED during a first emission period of an image frame, wherein the first emission period is indicative of light emissions of the first color according to image data; 
 a second operating electrical stimulus to the second LED during a second emission period of the image frame, wherein the second emission period is indicative of light emissions of the second color according to the image data; and 
 a reference electrical stimulus to the first LED during an off period of the image frame, wherein the off period is indicative of no light emissions associated with the image data; and 
 
 an analog to digital converter configured to receive a response characteristic of the first LED while the reference electrical stimulus is applied and generate temperature data indicative of a temperature of the first LED based on the response characteristic. 
 
     
     
       17. The electronic display of  claim 16 , comprising a plurality of mirrors configured to:
 during the first emission period, direct the first light to a plurality of pixel locations according to a first set of one or more bitplanes based on the image data; 
 during the second emission period, direct the second light to the plurality of pixel locations according to a second set of one or more bitplanes based on the image data; and 
 during the off period, direct the first light to one or more light attenuators and not to the plurality of pixel locations. 
 
     
     
       18. The electronic display of  claim 16 , wherein the off period is between the first emission period and the second emission period. 
     
     
       19. The electronic display of  claim 16 , wherein the off period is after the first emission period and the second emission period and before a third emission period of a second image frame directly subsequent the image frame. 
     
     
       20. The electronic display of  claim 16 , wherein the reference electrical stimulus comprises a reference voltage and the response characteristic comprises a current response, or the reference electrical stimulus comprises a reference current and the response characteristic comprises a voltage response.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 63/409,573, filed on Sep. 23, 2022, and entitled “Direct LED Temperature Sensing Systems and Methods,” the contents of which is hereby incorporated by reference in its entirety. 
    
    
     SUMMARY 
     The present disclosure generally relates to the temperature sensing of illuminators such as light emitting diodes (LEDs) within an electronic display. 
     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 accordance with embodiments of the present disclosure, it may be desirable to directly measure/estimate the temperature of an illuminator (e.g., backlight or projector) such as an LED, organic LED (OLED), or other light source within an electronic display. Such an illuminator (e.g., backlight or projector) may generate light for several different pixels, and a light regulator such as a mirror and/or a transmissive pixel may allow a portion of the generated light to be emitted based on a luminance value corresponding to the image data for the pixel. For example, a reflective technology display may have individually controlled color component illuminators that provide light to multiple pixels of the display panel via one or more reflective components (e.g., mirrors, light guides, etc.). However, during direct measurement (e.g., at and via the illuminator) of the temperature, a reference voltage or current may be applied, which may cause illumination of the illuminator separate from the light emissions associated with the image data. 
     As such, light regulators (e.g., mirrors or transmissivity regulating pixels) that adjust when and/or how much light is emitted from the electronic display may be used to block or redirect the light associated with application of the reference voltage or reference current. In other words, during moments when light would otherwise not be emitted from the electronic display, such as between light emissions of a single image frame, after light emissions of an image frame, and/or during any suitable moments that the illuminators would otherwise be off, the light regulators may be used to block or redirect light generated as a result of the reference current or reference voltage. As such, the temperature of an illuminator may be directly measured without or with reduced image artifacts associated with the application of the reference current or a reference voltage. 
    
    
     
       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 described below. 
         FIG.  1    is a schematic block diagram of an electronic device, in accordance with an embodiment; 
         FIG.  2    is a front view of a mobile phone representing an example of the electronic device of  FIG.  1   , in accordance with an embodiment; 
         FIG.  3    is a front view of a tablet device representing an example of the electronic device of  FIG.  1   , in accordance with an embodiment; 
         FIG.  4    is a front view of a notebook computer representing an example of the electronic device of  FIG.  1   , in accordance with an embodiment; 
         FIG.  5    are front and side views of a watch representing an example of the electronic device of  FIG.  1   , in accordance with an embodiment; 
         FIG.  6    is a block diagram of the image processing circuitry of  FIG.  1    including a temperature compensation block, in accordance with an embodiment; 
         FIG.  7    is a schematic view of an example reflective technology display, in accordance with an embodiment; 
         FIG.  8    is a schematic view of an example reflective technology display with a mirror array, in accordance with an embodiment; 
         FIG.  9    is a schematic view of an embodiment of an LED driving circuit, in accordance with an embodiment 
         FIG.  10    is a schematic view of an embodiment of an LED driving circuit, in accordance with an embodiment; 
         FIG.  11    is an example timing diagram for implementing reference voltages or currents between light emissions from the electronic display, in accordance with an embodiment; 
         FIG.  12    is an example timing diagram for implementing reference voltages or currents between light emissions from the electronic display, in accordance with an embodiment; and 
         FIG.  13    is a flowchart of an example process for directly measuring the temperature of an illuminator, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     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 “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 “some embodiments,” “embodiments,” “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. Furthermore, the phrase A “based on” B is intended to mean that A is at least partially based on B. Moreover, the term “or” is intended to be inclusive (e.g., logical OR) and not exclusive (e.g., logical XOR). In other words, the phrase A “or” B is intended to mean A, B, or both A and B. 
     Electronic devices often use electronic displays to present visual information. Such electronic devices may include computers, mobile phones, portable media devices, tablets, televisions, virtual-reality headsets, and vehicle dashboards, among many others. To display an image, an electronic display controls the luminance (e.g., brightness and/or color) at pixel locations based on corresponding image data. For example, an image data source may provide image data as a stream of pixel data, in which data for each pixel location indicates a target luminance. In some embodiments, the electronic display may include illuminators (e.g., backlights or projectors) that generate light for several different pixels, and each pixel may allow a portion of the generated light to be emitted (e.g., via mirrors and/or transmissivity regulating elements) based on a luminance value of the image data corresponding to the pixel. Such displays may include but are not limited to reflective technology displays (e.g., digital micro-mirror displays (DMDs), ferroelectric-liquid-crystal-on-silicon (FLCOS) display, etc.) and transmissive displays such as liquid crystal displays (LCDs). 
     An electronic display may utilize one or more illuminators (e.g., backlights, projectors, etc.) such as light emitting diodes (LEDs), organic LEDs (OLEDs), etc. to provide light for generating an image. However, the operation and/or output of such illuminators may vary based on their temperature. As such, it may be desirable to measure, estimate, or otherwise receive the temperature of one or more illuminators and utilize the temperature to compensate or alter one or more operations of the electronic device. In some scenarios, temperature sensors may be placed proximate an illuminator to estimate its temperature. However, the additional components of and/or real estate utilized by separate temperature sensors may increase manufacturing costs and/or be unviable for some implementations (e.g., based on space limitations). As such, directly measuring the temperature of the illuminator based on the voltage/current characteristics of the illuminator itself may increase the spatial efficiency, manufacturing efficiency, and/or efficacy of an electronic display with temperature sensed illuminators. 
     For example, in response to being supplied with a reference current or a reference voltage, an illuminator may exhibit a voltage response (e.g., forward voltage across the illuminator) or current response (e.g., current through the illuminator), respectively, indicative of the temperature of the illuminator. In either case, applying a reference voltage or a reference current to estimate the temperature directly (e.g., at and via the illuminator&#39;s response) may cause illumination of the illuminator, which may lead to image artifacts being displayed if perceived by a viewer. As discussed further below, the light regulators (e.g., mirrors or transmissivity regulating pixels) that adjust when and/or how much light is emitted from the electronic display may be used to block or redirect the generated light while the reference current or reference voltage is applied. As such, the temperature of the illuminator may be directly measured without or with reduced image artifacts associated with the application of the reference current or a reference voltage. 
     With the foregoing in mind,  FIG.  1    is an example electronic device  10  with an electronic display  12  having independently controlled color component illuminators (e.g., projectors, backlights, etc.). As will be described in more detail below, the electronic device  10  may be any suitable electronic device, such as a handheld electronic device, a tablet electronic device, a notebook computer, and the like. Thus, it should be noted that  FIG.  1    is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in the electronic device  10 . 
     The electronic device  10  may include one or more electronic displays  12 , input devices  14 , input/output (I/O) ports  16 , a processor core complex  18  having one or more processors or processor cores, local memory  20 , a main memory storage device  22 , a network interface  24 , a power source  26 , and image processing circuitry  28 . The various components described in  FIG.  1    may include hardware elements (e.g., circuitry), software elements (e.g., a tangible, non-transitory computer-readable medium storing instructions), or a combination of both hardware and software elements. As should be appreciated, the various components may be combined into fewer components or separated into additional components. For example, the local memory  20  and the main memory storage device  22  may be included in a single component. Additionally, the image processing circuitry  28  (e.g., a graphics processing unit, a display image processing pipeline, etc.) may be included in the processor core complex  18 . 
     The processor core complex  18  may be operably coupled with local memory  20  and the main memory storage device  22 . The local memory  20  and/or the main memory storage device  22  may include tangible, non-transitory, computer-readable media that store instructions executable by the processor core complex  18  and/or data to be processed by the processor core complex  18 . For example, the local memory  20  may include cache memory or random access memory (RAM) and the main memory storage device  22  may include read only memory (ROM), rewritable non-volatile memory such as flash memory, hard drives, optical discs, and/or the like. 
     The processor core complex  18  may execute instructions stored in local memory  20  and/or the main memory storage device  22  to perform operations, such as generating source image data. As such, the processor core complex  18  may include one or more general purpose microprocessors, one or more application specific processors (ASICs), one or more field programmable logic arrays (FPGAs), or any combination thereof. 
     The network interface  24  may connect the electronic device  10  to a personal area network (PAN), such as a Bluetooth network, a local area network (LAN), such as an 802.11x Wi-Fi network, and/or a wide area network (WAN), such as a 4G, LTE, or 5G cellular network. In this manner, the network interface  24  may enable the electronic device  10  to transmit image data to a network and/or receive image data from the network. 
     The power source  26  may provide electrical power to operate the processor core complex  18  and/or other components in the electronic device  10 . Thus, the power source  26  may include any suitable source of energy, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. 
     The I/O ports  16  may enable the electronic device  10  to interface with various other electronic devices. The input devices  14  may enable a user to interact with the electronic device  10 . For example, the input devices  14  may include buttons, keyboards, mice, trackpads, and the like. Additionally or alternatively, the electronic display  12  may include touch sensing components that enable user inputs to the electronic device  10  by detecting occurrence and/or position of an object touching its screen (e.g., surface of the electronic display  12 ). 
     The electronic display  12  may display a graphical user interface (GUI) of an operating system, an application interface, text, a still image, or video content. To facilitate displaying images, the electronic display  12  may include a display panel with one or more display pixels. Additionally, each display pixel may include one or more sub-pixels, which each control the luminance of a color component (e.g., red, green, or blue). As used herein, a display pixel may refer to a collection of sub-pixels (e.g., red, green, and blue subpixels) or may refer to a single sub-pixel. Moreover, a display pixel may include any components that generate, direct, or otherwise control light emission at a pixel location and may or may not be located at the pixel location. 
     As described above, the electronic display  12  may display an image by controlling the luminance of the sub-pixels based at least in part on corresponding image data. In some embodiments, the image data may be received from another electronic device, for example, via the network interface  24  and/or the I/O ports  16 . Additionally or alternatively, the image data may be generated by the processor core complex  18  and/or the image processing circuitry  28 . Moreover, in some embodiments, the electronic device  10  may include multiple electronic displays  12  and/or may perform image processing (e.g., via the image processing circuitry  28 ) for one or more external electronic displays  12 , such as connected via the network interface  24  and/or the I/O ports  16 . 
     The electronic device  10  may be any suitable electronic device. To help illustrate, one example of a suitable electronic device  10 , specifically a handheld device  10 A, is shown in  FIG.  2   . In some embodiments, the handheld device  10 A may be a portable phone, a media player, a personal data organizer, a handheld game platform, and/or the like. For example, the handheld device  10 A may be a smart phone, such as an iPhone® model available from Apple Inc. 
     The handheld device  10 A may include an enclosure  30  (e.g., housing) to, for example, protect interior components from physical damage and/or shield them from electromagnetic interference. Additionally, the enclosure  30  may surround, at least partially, the electronic display  12 . In the depicted embodiment, the electronic display  12  is displaying a graphical user interface (GUI)  32  having an array of icons  34 . By way of example, when an icon  34  is selected either by an input device  14  or a touch-sensing component of the electronic display  12 , an application program may launch. 
     Furthermore, input devices  14  may be provided through openings in the enclosure  30 . As described above, the input devices  14  may enable a user to interact with the handheld device  10 A. For example, the input devices  14  may enable the user to activate or deactivate the handheld device  10 A, navigate a user interface to a home screen, navigate a user interface to a user-configurable application screen, activate a voice-recognition feature, provide volume control, and/or toggle between vibrate and ring modes. Moreover, the I/O ports  16  may also open through the enclosure  30 . Additionally, the electronic device may include one or more cameras  36  to capture pictures or video. In some embodiments, a camera  36  may be used in conjunction with a virtual reality or augmented reality visualization on the electronic display  12 . 
     Another example of a suitable electronic device  10 , specifically a tablet device  10 B, is shown in  FIG.  3   . For illustrative purposes, the tablet device  10 B may be an iPad® model available from Apple Inc. A further example of a suitable electronic device  10 , specifically a computer  10 C, is shown in  FIG.  4   . For illustrative purposes, the computer  10 C may be a MacBook® or iMac® model available from Apple Inc. Another example of a suitable electronic device  10 , specifically a watch  10 D, is shown in  FIG.  5   . For illustrative purposes, the watch  10 D may be an Apple Watch® model available from Apple Inc. As depicted, the tablet device  10 B, the computer  10 C, and the watch  10 D each also includes an electronic display  12 , input devices  14 , I/O ports  16 , and an enclosure  30 . 
     As described above, the electronic display  12  may display images based at least in part on image data. Before being used to display a corresponding image on the electronic display  12 , the image data may be processed, for example, via the image processing circuitry  28 . In general, the image processing circuitry  28  may process the image data for display on one or more electronic displays  12 . For example, the image processing circuitry  28  may include a display pipeline, memory-to-memory scaler and rotator (MSR) circuitry, warp compensation circuitry, or additional hardware or software means for processing image data. The image data may be processed by the image processing circuitry  28  to reduce or eliminate image artifacts, compensate for one or more different software or hardware related effects, and/or format the image data for display on one or more electronic displays  12 . As should be appreciated, the present techniques may be implemented in standalone circuitry, software, and/or firmware, and may be considered a part of, separate from, and/or parallel with a display pipeline or MSR circuitry. 
     To help illustrate, a portion of the electronic device  10 , including image processing circuitry  28 , is shown in  FIG.  6   . The image processing circuitry  28  may be implemented in the electronic device  10 , in the electronic display  12 , or a combination thereof. For example, the image processing circuitry  28  may be included in the processor core complex  18 , a timing controller (TCON) in the electronic display  12 , or any combination thereof. As should be appreciated, although image processing is discussed herein as being performed via a number of image data processing blocks, embodiments may include hardware or software components to carry out the techniques discussed herein. 
     The electronic device  10  may also include an image data source  38 , a display panel  40 , and/or a controller  42  in communication with the image processing circuitry  28 . In some embodiments, the display panel  40  of the electronic display  12  may be a reflective technology display, a liquid crystal display (LCD), or any other suitable type of display panel  40 . In some embodiments, the controller  42  may control operation of the image processing circuitry  28 , the image data source  38 , and/or the display panel  40 . To facilitate controlling operation, the controller  42  may include a controller processor  44  and/or controller memory  46 . In some embodiments, the controller processor  44  may be included in the processor core complex  18 , the image processing circuitry  28 , a timing controller in the electronic display  12 , a separate processing module, or any combination thereof and execute instructions stored in the controller memory  46 . Additionally, in some embodiments, the controller memory  46  may be included in the local memory  20 , the main memory storage device  22 , a separate tangible, non-transitory, computer-readable medium, or any combination thereof. 
     The image processing circuitry  28  may receive source image data  48  corresponding to a desired image to be displayed on the electronic display  12  from the image data source  38 . The source image data  48  may indicate target characteristics (e.g., pixel data) corresponding to the desired image using any suitable source format, such as an RGB format, an αRGB format, a YCbCr format, and/or the like. Moreover, the source image data may be fixed or floating point and be of any suitable bit-depth. Furthermore, the source image data  48  may reside in a linear color space, a gamma-corrected color space, or any other suitable color space. As used herein, pixels or pixel data may refer to a grouping of sub-pixels (e.g., individual color component pixels such as red, green, and blue) or the sub-pixels themselves. 
     As described above, the image processing circuitry  28  may operate to process source image data  48  received from the image data source  38 . The image data source  38  may include captured images from cameras  36 , images stored in memory, graphics generated by the processor core complex  18 , or a combination thereof. Additionally, the image processing circuitry  28  may include one or more sets of image data processing blocks  50  (e.g., circuitry, modules, or processing stages) such as a temperature compensation block  52 . As should be appreciated, multiple other processing blocks  54  may also be incorporated into the image processing circuitry  28 , such as a color management block, a dither block, a burn-in compensation (BIC) block, a scaling/rotation block, etc. before and/or after the temperature compensation block  52 . The image data processing blocks  50  may receive and process source image data  48  and output display image data  56  in a format (e.g., digital format and/or resolution) interpretable by the display panel  40 . Further, the functions (e.g., operations) performed by the image processing circuitry  28  may be divided between various image data processing blocks  50 , and, while the term “block” is used herein, there may or may not be a logical or physical separation between the image data processing blocks  50 . 
     As discussed herein, the electronic display  12  may utilize one or more illuminators (e.g., backlights, projectors, etc.) such as light emitting diodes (LEDs), organic LEDs (OLEDs), etc. to generate an image. However, the operation and/or output of such illuminators may vary based on their temperature. As such, in some embodiments, the temperature compensation block  52  may be used to measure, estimate, or otherwise receive the temperature of one or more illuminators and utilize the temperature to compensate or alter one or more operations of the electronic device  10 . For example, the temperature compensation block  52  may receive voltage and/or current measurements associated with an illuminator and determine/estimate the temperature of the illuminator based thereon. Moreover, the temperature compensation block  52  may utilize the temperature of the illuminators to apply compensations to the image data and/or the supplied illuminator currents/voltages to account for temperature related effects (e.g., color shifts, timing alterations, etc.). As should be appreciated, as used herein, the temperature compensation block  52  may be considered as performing a standalone compensation/analysis or as a component or sub-component of any portion of the image processing circuitry  28  that utilizes the temperature of an illuminator in statistics, compensation, and/or data analysis. As non-limiting examples, such compensation/analysis may include color shift compensations, burn-in related aging statistics gathering, etc. 
     In general, an illuminator (e.g., backlight or projector) may generate light for multiple different pixels, and each pixel may allow a portion of the generated light to be emitted based on a luminance value corresponding to the image data for the pixel. In some embodiments, the electronic display  12  may include illuminators for multiple different color components (e.g., a red illuminator, a green illuminator, a blue illuminator, a white illuminator), and the light generated by each of the different color illuminators may be directed (e.g., via a light guide, one or more mirrors, via one or more color filters) to the pixels of the electronic display. Additionally or alternatively, the pixels may regulate an amount of light that is transmitted therethrough (e.g., via one or more color filters, polarizers, etc.) such that the light emitted from the electronic display  12  corresponds to the image data. As should be appreciated, such electronic displays  12  may include reflective technology displays (e.g., digital micro-mirror displays (DMDs), ferroelectric-liquid-crystal-on-silicon (FLCOS) display, etc.), liquid crystal displays (LCDs), or any suitable electronic display having illuminators with light directing/regulating components. 
     To help illustrate,  FIGS.  7  and  8    are schematic views of example reflective technology displays  60  having different color component illuminators  62 . In some embodiments, a reflective technology display  60  may include an illuminator layer  64 , a reflective layer  66 , and a pixel layer  68 , as in  FIG.  7   . For example, the illuminator layer  64  may include different color component illuminators  62  (e.g., a red illuminator  62 A, a green illuminator  62 B, and a blue illuminator  62 C, collectively  62 ) that generate light in their respective color. The reflective layer  66  may include one or more mirrors  70  that reflect the light generated by the illuminators  62  to one or more pixel locations  72  of the pixel layer  68 . At each pixel location  72 , the light generated by the illuminators  62  may be visible on the electronic display  12  according to the display image data  56 . For example, the mirrors  70  may reflect a portion of the generated light to a pixel location  72  for a certain duty cycle to provide a particular luminance level for an image frame. Additionally or alternatively, the pixel locations  72  may include active pixels that limit the amount of light passing therethrough (e.g., based on the display image data  56 ). 
     Furthermore, in some embodiments, the mirrors  70  may direct light from the illuminators  62  to either the pixel locations  72  or to one or more light attenuators  74 . A light attenuator  74  may include a heat sink and/or a light absorbing surface such as a black mask. If a pixel location  72  is not to receive light (e.g., based on the display image data  56 ), a mirror  70  may direct the light from the illuminator  62  to a light attenuator  74  instead of the pixel location  72 , effectively turning “off” the pixel at the pixel location  72  for that time. For example, an image frame may be divided into multiple sub-frames such that the mirrors  70  alternate between directing the generated light to the pixel location  72  and the light attenuator  74  such that, in the aggregate, the amount of time (e.g., duty cycle) that the pixel location  72  is emitting the generated light is proportional to the desired luminance output at the pixel location  72  (e.g., according to the display image data  56 ). Indeed, the same mirrors  70  may be used in a time-multiplexed way for different color channels. For example, the red illuminator  62 A may be on for a first period, the green illuminator  62 B may be on for a second period, and the blue illuminator  62 C may be on for a third period. Each mirror  70  may correspond to a pixel location  72  that may display red light during the first period, green light during the second period, and blue light during the third period. 
     In some embodiments, the mirrors  70  may be disposed in a mirror array  76 , as in  FIG.  8   . For example, the illuminators  62  may project light to a mirror array  76  having separate mirrors for different pixel locations  72 . Moreover, in some embodiments, a light guide  78  may further direct the reflected light from the mirror array  76  to the pixel locations  72  of the pixel layer  68  for viewing. Additionally, the mirror array  76  may direct the generated light to a light attenuator  74  or to the viewed portion of the pixel layer  68  via or sans light guide  78 . Although shown as a unidirectional light guide  78 , as should be appreciated, the light guide  78  may direct the light from the mirror array  76  in any suitable direction to be viewed at the corresponding pixel locations  72  on the electronic display  12 . 
     The mirror array  76  may be modulated such that the light emitted by the illuminators  62  appears as an image corresponding to the display image data  56 . For example, independent mirrors  70  of the mirror array  76  may switch between an on-state (e.g., directed toward the pixel locations  72 ) and an off-state (e.g., directed towards a light attenuator  74 ) based on the display image data  56 . In the on state, the mirrors  70  of the mirror array  76  may direct the light from the illuminators  62  to respective pixel locations  72 . In the off state, the mirrors  70  of the mirror array  76  may direct the light elsewhere, such as the light attenuator  74 , making the associated pixel location  72  appear dark. The mirrors  70  may be toggled between the on-state and the off-state quickly to create small bursts of light. The eyes of the viewer may integrate the light to form an image corresponding to the display image data  56 . 
     As should be appreciated, while discussed above as relating to reflective technology displays  60  and displays having multiple color component illuminators  62 , the techniques discussed herein are also applicable to electronic displays  12  having mono-colored illuminators  62  and/or transmissive displays such as LCD displays. Indeed, in some embodiments, the illuminator layer  64  may shine directly or indirectly at the pixel layer  68 , and individual pixels or sub-pixels (e.g., having different color component color filters) at the pixel locations  72  may regulate the amount and/or color of light transmitted therethrough and emitted from the electronic display  12 . Furthermore, the pixels may regulate (e.g., pulse-width modulate) the amount of time (e.g., duty cycle) that the pixel is actively allowing light to be transmitted through and emitted from the pixels according to a luminance value of the image data. 
     In general, an illuminator  62 , such as an LED  80 , may be powered via a power supply  82  to regulate the duty cycle and/or brightness level of the illuminator  62 , as in  FIG.  9   . LEDs  80  are popular illuminators  62  in electronic displays  12 , and a display panel  40  may include one or more color component LEDs  80  such as red, green, blue, and/or white LEDs  80  and/or a mono-colored backlight LED. For example, white LEDs  80  may be used with color filters in an LCD to generate different color outputs. The power supply  82  regulates an anode voltage  84 , V A , to the LED  80  such that a voltage differential  86 , V D , also known as the forward voltage, between the anode voltage  84  and a cathode voltage  88  induces a current flow  90 , I D , also known as a forward current, that powers the LED  80 . In general, the luminance of an LED  80  is proportional to the current flow  90  through the LED. In some embodiments, one or the other of the anode voltage  84  and the cathode voltage  88  may be held constant or modulated to adjust the brightness and/or duty cycle of the LED  80 . Additionally or alternatively, a current regulator  92  may regulate the current flow  90  to adjust the brightness and/or duty cycle of the illuminator  62 . As should be appreciated, the LED  80  may be operated based on adjusting the current flow  90 , the anode voltage  84 , and/or the cathode voltage  88 . For example, the power supply  82  and/or the current regulator  92  may be a part of or coupled to an LED driver that applies regulates the luminance output of the LED  80 . Furthermore, the forward voltages and/or forward currents for driving different LEDs  80  may vary based on type, model, and/or color. For example, the forward voltage of a green or blue LED is generally larger than that of a red LED (e.g., for a same brightness, the green or blue LED may use a larger forward voltage). Moreover, different LEDs  80  may have different forward voltages (e.g., voltage differential  86 ) due to different colors, use time, environmental temperature, etc. 
     In some embodiments, the temperature compensation block  52  may include or be coupled to temperature sensing or measurement components proximate an illuminator  62  (e.g., LED  80 ) to ascertain the temperature of the illuminator  62 . However, the additional components of and/or real estate utilized by separate, independent temperature sensors may increase manufacturing costs and/or be unviable for some implementations (e.g., based on space limitations). As such, in some embodiments, the temperature of an LED  80  may be derived directly from the voltage and/or current characteristics of the LED  80 . Indeed, in response to being supplied with a reference current (e.g., a reference current flow  90 ) or a reference voltage (e.g., reference voltage differential  86 ), an LED  80  may exhibit a voltage response (e.g., voltage differential  86  across the LED  80 ) or a current response (e.g., current flow  90  through the LED  80 ), respectively, that is indicative of the temperature of the LED  80 . For example, for a supplied reference current flow  90 , the forward voltage measurement (e.g., voltage differential  86 ) across electrodes of the LED  80  may decrease as the temperature of the illuminator increases. In some embodiments, to estimate the temperature of the LED  80 , an analog to digital converter  94  (ADC) may measure the voltage differential  86  in response to the supplied reference current flow  90 , and generate temperature data  96  (e.g., a digital signal indicative of the temperature of the LED  80 ) based thereon. As should be appreciated, while discussed herein in the context of temperature measurement, the digital signal may be indicative of the LED&#39;s response to a reference electrical stimulus and may be used for any suitable purpose. As a non-limiting example, the voltage differential  86  or other response characteristic (e.g., current response) may be utilized in analog or digital form for estimating an age (e.g., wear) of the LED  80 . 
     While LEDs  80  are discussed herein as example illuminators  62 , as should be appreciated, the techniques of the present disclosure may be applicable to any suitable illuminator  62  capable of direct temperature measurement/estimation via application of a reference voltage or reference current. Moreover, as should be appreciated, the specific voltage and current characteristics may vary based on the type and/or model of illuminator  62 , and different color component illuminators  62  may have different current/voltage responses for the same temperature. 
     Additionally, while  FIG.  9    is representative of a single LED  80 , as should be appreciated, the power supply  82 , current regulator  92 , ADC  94 , and/or other driving and measurement components may be shared by multiple LEDs  80 , as in  FIG.  10   .  FIG.  10    is a schematic view of an LED driving circuit  98  that may drive the LEDs  80 . The LED driving circuit  98  includes a power supply  82 , which may be a Buck-Boost converter, to provide power (e.g., anode voltage  84 ) for a red LED  80 A, a green LED  80 B, and a blue LED  80 C (cumulatively LEDs  80 ) that are connected to a common anode  100 . The LED driving circuit  98  may also include a capacitor  102 , C out , respective voltage control circuits  104 A,  104 B, and  104 C (cumulatively  104 ) for the red LED  80 A, green LED  80 B, and blue LED  80 C, and a current regulator  92  having respective current regulation circuits  106 A,  106 B, and  106 C for the red LED  80 A, green LED  80 B, and blue LED  80 C for the red LED  80 A, green LED  80 B, and blue LED  80 C. Each voltage control circuit  104  has a respective feedback loop coupled to the corresponding LED  80 . The respective feedback loops are used to track the respective forward voltages (e.g., voltage differentials  86 ) of the corresponding LEDs  80  by using the corresponding feedback loop to feed back the cathode voltages  88  of the corresponding LEDs  80  to the power supply  82 . For example, the cathode voltage  88  at the cathode end of the red LED  80 A may be fed back to the power supply  82  and used to track the voltage differential  86  of the red LED  80 A. 
     A current source  108 , I in , is used with a resistor  110 , R in , to provide an input voltage  112 , V in , to an operational amplifier  114  of the current regulator  92 . In some embodiment, the input voltage  112  may be a predefined value or variable depending on implementation. Respective emission transistors  116 A,  116 B, and  116 C (cumulatively  116 ) are used in the corresponding current regulation circuits  106  with corresponding power switches  118 A,  118 B, and  118 C (cumulatively  118 ) and ground switches  120 A,  120 B, and  120 C (cumulatively  120 ) to control the emission status of the corresponding LEDs  80 . For example, in the current regulation circuit  106 A of the red LED  80 A, the emission transistor  116 A is turned on when the power switch  118 A is closed and the ground switch  120 A is open. The ground switches  120  are used to discharge the gate voltages (or base voltage) at the emission transistor  116 . When the ground switch  120  is closed, the gate voltage of the associated emission transistor  116  is discharged and the emission transistor  116  is turned off. When an emission transistor  116  is turned on, for example via closing the power switch  118 , the associated LED  80  is connected to a respective dynamically adjustable resistor  122 A,  122 B, or  122 C (cumulatively  122 ) to generate an adjustable respective current flow  90 A,  90 B, or  90 C of the current regulation circuit  106  for the LED  80 . Furthermore, respective feedback switches  124 A,  124 B, and  124 C (cumulatively  124 ) may be used to provide a feedback voltage from the emitter end of the emission transistor  116  to the operational amplifier  114 . 
     As discussed above, in the example circuitry of  FIG.  10   , the cathode voltage  88  of each LED  80  may be fed back to the power supply  82  as part of a feedback loop. Moreover, by utilizing the anode voltage  84  and the cathode voltage  88  together, the voltage differential  86  may be ascertained and the temperature data  96  generated based thereon. For example, the power supply  82  may include an ADC  94  to convert the measured voltage differential  86  into a digital signal indicative of the temperature of the LED  80  when a reference current flow  90  is supplied. Indeed, as discussed above, the temperature of the LED  80  may be determined by supplying a reference voltage or reference current and measuring the current response or the voltage response, respectively. 
     However, application of a reference voltage or a reference current (e.g., a reference electrical stimulus) to the LED  80  (e.g., to estimate the temperature directly at and via the illuminator&#39;s response) may lead to illumination of the LED  80 , which may lead to image artifacts being displayed if perceived by a viewer. As discussed further below, light regulators (e.g., mirrors  70  or transmissivity regulating pixels) that adjust when and/or how much light is emitted from the electronic display  12  may be used to block or redirect the generated light (e.g., via the light attenuators  74 ) while the reference current or reference voltage is applied. In other words, during moments when light would otherwise not be emitted from the electronic display  12 , such as between LED emissions of a single image frame, after light emissions of the image frame, and/or during any moments that the LEDs  80  would otherwise be off, the light regulators may be used to block or redirect light generated as a result of the reference current or reference voltage to maintain the appearance of off LEDs  80 . As such, the temperature of an illuminator  62  may be directly measured without or with reduced image artifacts associated with the application of the reference current or a reference voltage. 
       FIGS.  11  and  12    are example timing diagrams  126 ,  128  for implementing reference voltages or currents between light emissions  130  from the electronic display  12 . As discussed herein, the electronic display  12  may display an image frame by modulating the amount of time each color LED  80  has light emitted from a pixel location  72 . In some embodiments, a set of bitplanes  132  may be utilized to set the arrangement of mirrors  70  and/or pixel transmissivities that control the light emitted from the pixel locations  72 . Each bitplane  132  may be indicative of a set of mirror activations and/or pixel activations. For example, a bitplane  132  may set a portion of the mirrors  70  to reflect light generated by an LED  80  to a respective portion of pixel locations  72 , and set other mirrors  70 , associated with other pixel locations  72 , to reflect the light to the light attenuator(s)  74 . As such, the bitplane  132  may designate certain pixel locations  72  as “on” and other pixel locations as “off”. During an image frame, multiple bitplanes  132  for each color component may be implemented such that, in the aggregate, the relative on/off time for each pixel location  72  is indicative of the display image data  56  for each color component and thus the image. As should be appreciated, the human eye may temporally average the light emissions to perceive the image over the image frame. 
     In some scenarios, the frame length  134  of the image frame may be longer than the emission period  136  of the light emissions  130  of the LEDs  80 , leaving off periods  138  between light emissions  130  associated with displaying the image. As used herein, the frame length  134  of the image frame is the time between starts of emission periods  136  associated with separate image frames and includes the off periods  138  after and/or between emission periods  136  of the same image frame. The off periods  138  are indicative of moments where no light is desired to be emitted from the pixel locations  72 . During the off periods  138 , reference voltages and/or reference currents may be applied and temperature data  96  generated based on the response of the LEDs  80 . The reference voltages and/or currents may cause reference emissions  140 , and an off bitplane  142  may set mirrors  70  and/or pixel transmissivities to the off positions such that reduced or no light is emitted from the pixel locations  72 . As such, the temperature of the LEDs  80  may be directly measured during the image frame by utilizing off periods  138  between emission periods  136  associated with the display image data  56 . As shown in the timing diagram  126  of  FIG.  11   , the reference emissions  140 , associated with temperature measurements may be separated or grouped. Moreover, the temperature of each color LED  80  may be measured in the same off period  138  or in individual off periods  138 . 
     Furthermore, as shown in the timing diagram  128  of  FIG.  12   , in some scenarios, the emission periods  136  for the different color components may be separated by off periods  138 . As such, in some embodiments, temperature measurements, and associated reference emissions  140 , may occur between emission periods  136  of the same image frame. Moreover, as should be appreciated, the temperature measurements, and associated reference emissions  140 , may occur at any suitable moment during the off periods  138 . For example, the off bitplane  142  may occur immediately after an emission period  136  such that the LED  80  being measured for temperature may be set at or maintained at the reference voltage/current immediately after the emission period  136  of that LED  80  or any LED  80  may be set to the reference voltage/current for measurement at any suitable time after the off bitplane  142  is implemented. Furthermore, as should be appreciated, the temperature measurements may be made during each off period  138 , periodically after a number of image frames, periodically in time, and/or when requested (e.g., by the temperature compensation block  52 ). Additionally, while discussed above as measuring the temperatures of the LEDs  80  individually, if implemented with separate LED driving circuits  98  and/or response measurement components (e.g., ADCs  94 ), the temperature of multiple LEDs  80  may be measured simultaneously while the off bitplane  142  is engaged. 
       FIG.  13    is a flowchart  144  of an example process for directly measuring the temperature of an illuminator  62 . During an off period  138  of an image frame (e.g., otherwise having no light emissions  130 ), an off bitplane  142  may be implemented (process block  146 ). For example, the off bitplane  142  may adjust mirrors  70  (e.g., of a mirror array  76 ) to direct light to light attenuators  74  instead of pixel locations  72 . Additionally or alternatively, the off bitplane  142  may adjust pixel transmissivities to block all or a portion of the light generated by the illuminators  62 . A reference voltage or reference current may be applied to the illuminator  62  (process block  148 ), and the current response and/or voltage response of the illuminator  62  may be measured (process block  150 ). Temperature data  96  indicative of the temperature of the illuminator  62  may be generated based on the current response and/or voltage response (process block  152 ). Additionally, operation of the electronic display  12  may be adjusted (e.g., via the temperature compensation block  52 ) based on the temperature data  96  (process block  154 ). 
     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 noted that, although LEDs  80  and LED drivers are used in the embodiments described above, other illuminators and their drivers may use the techniques presented above. Moreover, although the above referenced flowchart  144  is shown in a given order, in certain embodiments, process/decision blocks may be reordered, altered, deleted, and/or occur simultaneously. Additionally, the referenced flowchart  144  is given as an illustrative tool and further decision and process blocks may also be added depending on implementation. 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. 
     It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Metadata:
Filing Date: 20230614
Publication Date: 20240827
Grant Date: 20240827
Priority Date: 20220923
Inventors: PIPER, JOHAN L
HAZEGHI, ARASH
ADJIWIBAWA, ADAM
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G3/346", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2310/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2310/0235", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0666", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2310/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3225", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G3/3225", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2310/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/346", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3225", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 90359629