Patent Publication Number: US-2017372659-A1

Title: Reducing burn-in of displayed images

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/354,652 filed Jun. 24, 2016, which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The various embodiments described in this document relate to electronic displays. In particular, embodiments relate to preventing display degradation due to screen or image burn-in. 
     BACKGROUND OF THE INVENTION 
     Many types of electronic displays are susceptible to screen burn-in, wherein certain areas of the screen become permanently discolored because of cumulative non-uniform usage of pixels. For example, prolonged display of an object in the same location can create a permanent ghost-like image of the object (even when the object isn&#39;t displayed) or otherwise degrade image quality. Extended activation of pixels may cause loss of luminance. Accordingly, if pixel use is non-uniform, some pixels may lose more luminance than others, causing discoloration of some areas of the screen. Extended display of a monochrome image may exacerbate the problem. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which: 
         FIGS. 1-6  illustrate an exemplary sequence of frames, including a display object, that swap illuminated sets of pixels and non-illuminated sets of pixels to reduce screen burn-in; 
         FIG. 7  illustrates, in block diagram form, components of a system that swaps illuminated sets of pixels and non-illuminated sets of pixels to reduce screen burn-in; and 
         FIG. 8  is a flow chart illustrating an exemplary method of swapping illuminated sets of pixels and non-illuminated sets of pixels to reduce screen burn-in. 
     
    
    
     DETAILED DESCRIPTION 
     This document describes embodiments that relate to preventing or otherwise reducing screen burn-in. Embodiments generate an object in a portion of an electronic display. Generating the object includes forming the shape using a pattern of illuminated and non-illuminated pixels. Each set of illuminated pixels is separated from another set of illuminated pixels by a set of non-illuminated pixels. In other words, the object appears as a shape formed by shading or fill of alternating illuminated and non-illuminated sets of pixels. In response to a swap event, embodiments generate the object in the portion of the electronic display by swapping illuminated and non-illuminated sets of pixels. For example, in response to a change in shape of the object, embodiments illuminate pixels within the sets that were previously non-illuminated and do not illuminate pixels within the sets that were previously illuminated. As a result, no particular pixel remains activated for too long, thus limiting or avoiding burn-in. 
       FIGS. 1-6  illustrate an exemplary sequence of frames, including a display object, that swap illuminated sets of pixels and non-illuminated sets of pixels to reduce screen burn-in. In particular, the exemplary sequence of frames is an animation including display objects representing two stylized eyes on electronic display  100 . Each frame displays sets of alternating illuminated horizontal lines and non-illuminated horizontal lines to form right eye  115  and left eye  120 . Embodiments swap the on/off pattern of illuminated and non-illuminated lines, so that no single pixel is illuminated for the entire sequence. 
     In this illustrated sequence of frames, the swap takes place simultaneously with a blink effect, as shown in  FIG. 3 , so that the swap is less noticeable to a viewer. For example,  FIG. 1  illustrates two sets of illuminated lines  105  alternating with non-illuminated lines  110  to form right eye  115  and left eye  120 , depicting two eyes in a wide-open state to the viewer.  FIG. 2  illustrates a change in shape of the display objects by altering the number and/or length of the illuminated lines (or otherwise changing the number and/or size of the sets of illuminated pixels). This change in shape of the display objects presents to the viewer the pair of eyes as narrowing or otherwise beginning to close.  FIG. 3  illustrates further change in shape of the display objects by altering the number and/or length of the illuminated lines. This change in shape of the display objects presents to the viewer the pair of eyes as closed mid-blink.  FIG. 4  illustrates further change in shape of the display objects by altering the number and/or length of the illuminated lines. This change in shape of the display objects presents to the viewer the pair of eyes as opening following the blink. Embodiments execute the swap of illuminated and non-illuminated lines simultaneously with or otherwise in response to the blink. For example, electronic display  100  in  FIG. 4  illustrates horizontal lines  105 , which were illuminated in  FIGS. 1-2 , as no longer being illuminated and horizontal lines  110 , which were not illuminated in  FIGS. 1-2 , as now illuminated. The swap of illuminated and non-illuminated lines persists through the further changing in shape of the display objects by altering the number and/or length of the illuminated lines in  FIGS. 5-6 . This change in shape of the display objects presents to the viewer the pair of eyes as opening further following the blink and returning to a wide-open state. 
     In summary, in  FIGS. 1-2  (pre-blink), embodiments illuminate a first set of horizontal lines and in  FIGS. 4-6  (post-blink), embodiments illuminate an opposite set of horizontal lines. As a result, the wide-open eyes generated on a portion of electronic display  100  as shown in  FIG. 1  are illustrated with the opposite set of lines in that portion of electronic display as shown  FIG. 6 . This swap prevents prolonged activation of a set of pixels, reducing the likelihood of screen burn-in, while maintaining the display of objects in that portion of electronic display  100 . The intermediate sequence of frames temporarily changing the shape of the objects provides a way for the swap to occur in a less noticeable manner. It would be difficult for a viewer to perceive the swap of illuminated and non-illuminated sets of pixels when the swap is performed during such a change in shape of the display object(s). The blink effect is just one example of mechanisms that can hide or minimize noticeability of the swapping of illuminating and non-illuminated lines. In other embodiments, the swap may be performed gradually (e.g., one pair of illuminated and non-illuminated sets swapped at a time), or it can be performed without an attempt to hide it. 
     While  FIGS. 1-6  illustrate an animation of blinking eyes in a sequence of six frames, other embodiments may include another number of intermediate frames to display the various stages of change in shape of each eye as the eyes close or open. For example, additional frames in the animation sequence may include the eyes in intermediate shapes between those depicted. 
     While  FIGS. 1-6  illustrate display objects formed by parallel horizontal lines, other arrangements are possible. For example, vertical lines or lines of any orientation can be used instead of horizontal lines. The sets of pixels may form shapes as well, such as squares, concentric circles, etc. 
     Swapping on/off patterns of illumination may take place according to any suitable periodic arrangement or may be triggered by scene changes or any other suitable events. For example, an author, artist, animator, or other individual may manually encode a swap event during the display and/or changing display of one or more objects. Alternatively, embodiments may automatically trigger a swap event based on display content. 
     In an embodiment including the manual approach, an individual embeds a swap command in the display content stream or otherwise in the parameters used to draw objects on the display. When the swap command is encountered, the software used to draw the object performs the swap. The author, artist, animator, or other individual can choose to insert the swap command at particular times in the display of one or more objects when he or she feels a swap will be least noticeable by a viewer. For example, as described in this document, the animation of a blinking eye may include a swap command when/once the eye is closed. 
     In an embodiment including the automated approach, software automatically analyzes the content stream or animation to determine if particular frames meet certain criteria for being a suitable time for a swap. For example, if a set of one or more frames include a blank screen, or if a frame closely matches a design predetermined to be appropriate for a swap (such as a blink as depicted in  FIG. 3 ), then the swap can be automatically triggered in response to or otherwise at the time that frame is displayed. The automated approach thus avoids the need for the author, artist, animator, or other individual to specify swap times or even to be aware of screen burn-in or pattern swapping. 
       FIG. 7  illustrates, in block diagram form, components of system  700  that swaps illuminated sets of pixels and non-illuminated sets of pixels to reduce screen burn-in. For example, system  700  may include a computer, mobile device, and/or other consumer electronics device that has the components described in this document. 
     System  700  includes one or more processing units  705 . Processing unit(s)  705  may include a central processing unit (CPU), graphics processing unit (GPU), microprocessor, microcontroller, system on a chip, and/or another integrated circuit. 
     System  700  also includes electronic display  100  coupled to processing unit(s)  705 . For example, electronic display  100  may be a liquid crystal display (LCD), light emitting diode (LED) display, organic LED (OLED) display, plasma display panel (PDP) or other type of display. In one embodiment, electronic display  100  is monochromatic. 
     System  700  also includes memory/storage  715 . Memory/storage  715  may include one or more of volatile and non-volatile memories, such as Random Access Memory (RAM), Read Only Memory (ROM), a solid-state disk (SSD), Flash, Phase Change Memory (PCM), or other types of data storage. Memory/storage  715  may store data, metadata, and/or programs for execution by the processing unit(s)  705 . For example, memory/storage  715  stores program module(s) such as display driver  720  and burn-in prevention module  725 . 
     In one embodiment, display driver  720  is a computer program that provides an interface for and controls output to electronic display  100 . Display driver  720  enables an operating system or other computer program to access the functionality of electronic display  100 . Alternatively, or additionally, processing unit(s)  705  provide a hardware interface to electronic display  100 . 
     In one embodiment, burn-in prevention module is a computer program that executes a swap command or automatically triggers a swap event based on display content. Examples of manual and automatic swap events are described with reference to the other drawings. 
     While this document illustrates and describes embodiments implemented using software modules, alternate embodiments of the invention may be implemented in, but not limited to, hardware or firmware utilizing an FPGA, ASIC, and/or processing unit(s)  705 . Modules and apparatus of hardware or software implementations can be divided or combined without significantly altering embodiments of the invention. One or more buses interconnect components of system  700 . Fewer or more buses than illustrated may interconnect the components. In one embodiment, one or more components may connect to one another wirelessly. 
       FIG. 8  is a flow chart illustrating exemplary method  800  of swapping illuminated sets of pixels and non-illuminated sets of pixels to reduce screen burn-in. At block  805 , processing unit(s)  705  generate one or more display objects on electronic display  100 . Processing unit(s)  705  generate the display object(s) by instructing electronic display  100  to display alternating sets of illuminated and non-illuminated pixels. Each set of illuminated pixels is separated by a set of pixels that are not illuminated. Right eye  115  and left eye  120  are examples of such display objects. 
     At block  810 , processing unit(s)  705  determine whether a swap event has occurred. For example, processing unit(s)  705  detect a swap event in response to receiving a manual swap command. Alternatively, burn-in prevention module  725  automatically triggers a swap event in response to a change in shape of the object(s) as described above. 
     If processing unit(s)  705  determine a swap event has not occurred, method  800  returns to block  805  to continue generation of the display object(s). The continued generation of the display object(s) may include, for example, a change in the shape of the object(s). For example,  FIGS. 1-2  illustrate continued generation of display objects that include a change in size of the objects but without triggering a swap event. 
     If processing unit(s)  705  determine a swap event has occurred, at block  815 , processing unit(s) generate the display object(s) formed by alternating sets of illuminated and non-illuminated pixels, such that one or more sets of pixels that were previously illuminated are now not illuminated and one or more sets of pixels that were previously not illuminated are now illuminated. 
     It will be apparent from this description that aspects of the inventions may be embodied, at least in part, in software. That is, computer-implemented method  800  may be carried out in one or more computer systems or other data processing systems, such as system  700 , in response to its processor executing sequences of instructions contained in a memory or another non-transitory machine-readable storage medium. The software may further be transmitted or received over a wired or wireless connection via a network interface. In various embodiments, hardwired circuitry may be used in combination with the software instructions to implement the present embodiments. Thus, the techniques are not limited to any specific combination of hardware circuitry and software, or to any particular source for the instructions executed by a node and/or central controller. It will also be appreciated that additional components, not shown, may also be part of system  700 , and, in certain embodiments, fewer components than that shown in  FIG. 7  may also be used in system  700 . 
     In the foregoing specification, the invention(s) have been described with reference to specific exemplary embodiments thereof. Various embodiments and aspects of the invention(s) are described with reference to details discussed in this document, and the accompanying drawings illustrate the various embodiments. The description above and drawings are illustrative of the invention and are not to be construed as limiting the invention. References in the specification to “one embodiment,” “an embodiment,” “an exemplary embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but not every embodiment may necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, such feature, structure, or characteristic may be implemented in connection with other embodiments whether or not explicitly described. Additionally, as used in this document, the term “exemplary” refers to embodiments that serve as simply an example or illustration. The use of exemplary should not be construed as an indication of preferred examples. Blocks with dashed borders (e.g., large dashes, small dashes, dot-dash, dots) are used to illustrate virtualized resources or, in flow charts, optional operations that add additional features to embodiments of the invention. However, such notation should not be taken to mean that these are the only options or optional operations, and/or that blocks with solid borders are not optional in certain embodiments of the invention. Numerous specific details are described to provide a thorough understanding of various embodiments of the present invention. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present inventions. 
     Embodiments according to the invention are, in particular, disclosed in the claims directed to a method, a storage medium, and a system, wherein any feature mentioned in one claim category, e.g., the system, can be claimed in another claim category, e.g., the method, as well. The dependencies or references in the claims are chosen for formal reasons only. Any subject matter resulting from a deliberate reference back to any previous claims (in particular multiple dependencies) can be claimed as well, so that any combination of claims and the features thereof are disclosed and can be claimed regardless of the dependencies chosen in the attached claims. The subject-matter which can be claimed comprises not only the combinations of features as set out in the attached claims but also any other combination of features in the claims, wherein each feature mentioned in the claims can be combined with any other feature or combination of other features in the claims. Furthermore, any of the embodiments and features described or depicted herein can be claimed in a separate claim and/or in any combination with any embodiment or feature described or depicted herein or with any of the features of the attached claims. 
     It will be evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. For example, the methods described in this document may be performed with fewer or more features/blocks or the features/blocks may be performed in differing orders. Additionally, the methods described in this document may be repeated or performed in parallel with one another or in parallel with different instances of the same or similar methods.