Systems and methods for controlling current in display devices

Abstract

Procedure (58) encompassing: Receiving drive current values ​​linked to subpixels in a display (10); Identify (62) at least one proportion of image data (44) comprising a plurality of pixels with substantially uniform brightness and substantially uniform color coordinates; Reducing (64) at least some of the drive current values ​​corresponding to the proportion of image data (44); Do not reduce at least some of the drive current values ​​if the portion of the image data (44) does not include substantially uniform brightness and substantially uniform color coordinates; and Supplying the subpixels with the drive currents (48) that correspond to the drive current values.

Description

background

[0001] The present disclosure relates generally to energy-efficient display devices and more specifically to an automatic current limit (ACL) control that reduces the overall power consumption in organic light-emitting diode (OLED) display devices.

[0002] This section is intended to introduce the reader to various aspects of the prior art that may relate to different aspects of the present disclosure, which are described and / or claimed below. It is assumed that this discussion will be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, these statements should be understood in this light and not as an admission of the prior art.

[0003] Organic light-emitting diode (OLED) displays produce light in response to an electrical signal, so an OLED display will produce brighter light in response to a stronger electronic signal (e.g., current). Therefore, an OLED display consumes a significant amount of power when displaying bright images. Similarly, an OLED display consumes a lot of power when displaying images with a high proportion of white pixels (e.g., mimicking the appearance of a book page or sheet of paper in a word processing document) or when increasing the overall brightness of the OLED display to improve viewing in bright environments. In addition to being an inefficient use of power, this high power consumption in OLED displays can be detrimental to their performance.For example, using high power reduces battery life and can lead to problems with thermal heating of the electronic device attached to the OLED display.

[0004] Although conventional automatic current limiting (ACL) circuits can provide some power savings in OLED displays, the resulting image reproduced by the display device may be objectionable to a viewer. For example, in a photographic image or an application that relies on a realistic reproduction of the colors and brightness levels of an image, the application of the conventional ACL approach can reduce the overall brightness of the displayed image, making it difficult to discern subtle differences in the colors of the displayed image and thus reducing the quality of the reproduced image on the OLED display.

[0005] US 2007 / 0279372A1 describes a display system comprising: a transmissive display, wherein the display comprises a plurality of colored subpixels, each such colored subpixel being essentially a broadband bandpass filter; a transmissive display controller, wherein the display controller provides signals to the transmissive display to adjust the amount of transmittance of each of the colored subpixels; a backlight, wherein the backlight illuminates the transmissive display; a backlight controller, wherein the controller provides signals to the backlight to modulate the amount of illumination supplied by the backlight to the transmissive display; a peak monitoring module for measuring image data and extracting the image area envelope to provide intermediate backlight data signals to the backlight controller to match the image area envelope;and a device for normalizing display image data signals according to the intermediate backlight data signals and providing the normalized image data as intermediate display data.

[0006] Further examples are described in US 2011 / 0 115 835 A1 and in US 2006 / 0 262 147 A1. Summary

[0007] The invention is defined by the independent claims. Preferred embodiments are described by the dependent claims. A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented only to provide the reader with a brief summary of these particular embodiments and that these aspects are not intended to limit the scope of this disclosure. In fact, this disclosure may include a multitude of aspects not set forth below.

[0008] The present disclosure relates generally to a control system that reduces the drive current supplied to each subpixel or a number of specified subpixels of the display, based on various factors relating to the image(s) being displayed. In this way, the control system can provide significant power savings while maintaining the quality of the displayed images. Furthermore, the reduction in power can lead to an improved lifespan of the displays and reduce the heat generated by the display during operation.In one embodiment, the control system can receive information specifying the type of application displaying images, the type of image being displayed, the amount of power consumed by the display, the level of ambient light reflected by the display, or similar information. Upon receiving this information, the control system can determine a degree of current reduction for each subpixel of the display based on these inputs.

[0009] For example, in one embodiment, the control system can analyze the application being displayed. If the application displays a large amount of white content (e.g., email, ebook, reader, word processor, and spreadsheet), the control system can uniformly reduce the current available to drive the display because the overall reduction in white levels in the background should not detract from the image quality of the text displayed by the application. Alternatively, if the application is designed to display colors more accurately (e.g., viewing photographic or video content), the control system can maintain the current available to drive the display in order to preserve the integrity of the displayed images.

[0010] In another embodiment, the control system can analyze a displayed image and identify subpixels in the image that are substantially similar. The control system can then reduce the current available to drive the substantially similar subpixels while maintaining the current available to drive the subpixels that are not substantially similar.

[0011] In yet another embodiment, the control system can measure a signal representing the amount of ambient light reflected by the display. The control system can then modify the extent to which the current applied to the display is reduced based on the measured ambient light level. For example, the control system can limit the current driving the display less in bright environments compared to dark environments. By reducing the current available to drive specific pixels, the control system can reduce the brightness or certain aspects of the image so that the displayed image may be more acceptable to a viewer. Accordingly, the control system can be useful for reducing the power consumed by the display in ways that render the displayed images unobtrusive to the viewer. Brief description of the drawings

[0012] Various aspects of the revelation can be better understood after reading the following detailed description and referring to the drawings in which: Fig. 1. A block diagram of components of an electronic device is in accordance with an embodiment; Fig. 2. A front view of a handheld electronic device is in accordance with one embodiment; Fig. 3. A computer view is in accordance with a form of execution; Fig. 4 is a data flow diagram representing inputs that use an automatic current limit (ACL) control to determine the drive currents of a display, in accordance with an embodiment; Fig. 5 a flowchart that represents a method for reducing an amount of drive currents sent to a display, based on an application displayed on the display, in accordance with an embodiment; Fig. 6 a flowchart that represents a method for reducing an amount of drive currents sent to a display, based on an image displayed on the display, in accordance with an embodiment; Fig. 7 provides two screenshots illustrating an example of the effect of reducing the drive currents sent to the display, based on an image displayed in accordance with an embodiment; Fig. 8 is a flowchart that represents a method for reducing drive currents sent to a display based on power consumption characteristics of the display in accordance with an embodiment; Fig. 9 is a flowchart that represents a method for reducing drive currents sent to a display, based on brightness and color characteristics of images reproduced on the display, in accordance with an embodiment; and Fig. 10 is a flowchart that represents a method for determining an estimate of the brightness of a display using a sampling algorithm in accordance with an embodiment. Fig. 11 is a flowchart that represents a method for reducing drive currents sent to a display based on existing ambient light conditions in accordance with an embodiment. Detailed description of the specific embodiments

[0013] One or more specific embodiments are described below. In an effort to provide a brief description of these embodiments, not all features of an actual implementation are described in the specification. It should be understood that, as in any engineering or design project, the development of any such actual implementation requires numerous implementation-specific decisions to be made in order to achieve the specific objectives of the developers, such as compliance with system-related and business-related constraints, which may vary from one implementation to the next. Furthermore, it should be understood that such a development endeavor may be complex and time-consuming, but could nevertheless be a routine undertaking of design, manufacture, and fabrication for the person skilled in the art who benefits from this disclosure.

[0014] The present disclosure relates to systems, displays, and methods for reducing drive currents supplied to an electronic display in order to improve the power efficiency and / or appearance of the display. Organic light-emitting diode (OLED) displays can use an array of OLEDs to display an image along the display. Each OLED subpixel emits light of a specific color and brightness based on drive currents supplied to the OLEDs. In one embodiment, red, green, and blue emitters can be used to display a range of colors. In another embodiment, the OLED display can emit white light, and color filters or fluorescent materials can be used to convert the white light into individual colors.The emitted colors can be red, green, and blue, but additional white subpixels can also be used. In yet another embodiment, red, green, and blue emitters can be used to emit a range of colors, and these colors can be further refined by passing them through a set of color filters, so that each emitted color is paired with a specific color from a color filter.

[0015] The drive currents supplied to each OLED subpixel can be regulated by an automatic current limit (ACL) controller in a display driver. The ACL controller can reduce the power consumption of the OLED display by reducing the total drive current supplied to the OLED display or by limiting the current to all OLED subpixels proportionally. However, instead of uniformly reducing the drive current supplied to each OLED, regardless of the image being displayed and / or viewing conditions, the ACL controller can reduce the drive current supplied to each OLED subpixel or specified OLED subpixels in a way that provides power savings while maintaining the integrity of the images displayed on the OLED display.

[0016] A variety of electronic devices can accommodate the OLED displays that feature ACL control. An example of a suitable electronic device might include various internal and / or external components that contribute to the device's functionality. Fig. Figure 1 is a block diagram illustrating the components that may be present in such an electronic device 8 and which may allow the device 8 to function in accordance with the techniques discussed herein. The person skilled in the art will understand that various functional blocks, which are in Fig. 1. Hardware elements (including circuits), software elements (including computer code stored on a computer-readable medium), or a combination of both hardware and software elements can be shown. It should also be noted that Fig. Figure 1 is only an example of a particular implementation and is intended only to illustrate the types of components that may be present in a device 8. For example, in the illustrated embodiment shown here, these components may include a display 10, I / O ports 12, input structures 14, one or more processors 16, a storage device 18, non-volatile memory 20, one or more light sensors 22, a network device 24, a power source 26, and an automatic current limiter (ACL) 28.

[0017] With respect to each of these components, the display 10 can be used to display various images generated by the device 8. In one embodiment, the display 10 can be an organic light-emitting diode (OLED) display. An OLED display can include a number of pixels or picture elements that can be used to display images on the display 10. In an OLED display, each pixel can be composed of three pixel components known as subpixels, each capable of displaying red, green, and blue colors. Alternatively, four pixel components, namely red, green, blue, and white, can be used. Each OLED subpixel can display its respective color using an emitting electroluminescent layer (i.e., a film of an organic compound) that emits light in response to an electric current.The color of the light being viewed can be the light emitted directly from the OLED subpixels, or the color that has been modified by passing through a color filter containing an absorbing or fluorescent material. Therefore, when bright images are displayed on an OLED screen, relatively high power levels can be utilized by the screen.

[0018] The I / O ports 12 can include ports configured to connect a variety of external devices, such as a power source, headset or headphones, or other electronic devices 8 (such as handheld devices and / or computers, printers, projectors, external displays, modems, docking stations, etc.). The input structures 14 can include the various devices, circuits, and paths through which user input or feedback is provided to the processor 16. The input structures 14 can be configured to control a function of the device 8, of applications running on the device 8, and / or of any interfaces or devices connected to or used by the electronic device 8.

[0019] The processor(s) 16 can provide the processing capability to execute the operating system, programs, user and application interfaces, and any other functions of the electronic device 8. The instructions or data to be executed by the processor(s) 16 can be stored on a computer-readable medium, such as memory 18. Memory 18 can be provided as volatile memory, such as random access memory (RAM), and / or as non-volatile memory, such as read-only memory (ROM). The components can further include other forms of computer-readable media, such as non-volatile memory 20 for the persistent storage of data and / or instructions. Non-volatile memory 20 can include flash memory, a hard disk, or any other optical, magnetic, and / or solid-state storage media.The non-volatile memory 20 can be used to store firmware, data, software, wireless connection information and any other suitable data.

[0020] The embodiment, which in Fig. As illustrated in Figure 1, the device can also include one or more light sensors 22. The light sensors 22 can include sensors such as photodetectors, photodiodes, photoresistors, photocells, or any other sensor capable of detecting ambient light. In various embodiments, the light sensors 22 can be arranged in the substrate so that they can receive light from the direction of the substrate, from the direction opposite to the substrate, or from both. In certain embodiments, a camera can be present in the device and can serve as a light sensor.

[0021] The components that are in Fig. The components shown in Figure 1 also include a network device 24, such as a network controller or a network interface card (NIC). The network device 24 can be a Wi-Fi device, a radio frequency device, a Bluetooth device, a cellular communication device, or similar. The network device 24 can allow the electronic device 8 to communicate over a network, such as a local area network (LAN), a wide area network (WAN), or the internet. Furthermore, the components can also include a power source 26, such as a battery or AC power.

[0022] To prevent excessive power consumption by the display 10, the electronic device 8 can also include the automatic current limiter (ACL) 28. The ACL 28 can monitor the total power or current used by the display 10 and can reduce the overall power consumption of the display 10 by controlling the current supplied to the display 10. In one embodiment, the ACL 28 can estimate the power consumption expected for an image frame to be displayed on the display 10. The ACL 28 can limit the drive current supplied to each subpixel of the display 10 based on various factors. Additional details regarding the ACL 28 are described below with reference to the Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10 to Fig. 11 discussed.

[0023] With the preceding events in mind, illustrated Fig. 2 an electronic device in the form of a handheld device 30, here a mobile phone.

[0024] It should be understood that, while the illustrated handheld device is provided in the context of a mobile phone, other types of handheld devices (such as media players for playing music and / or video, personal data organizers, handheld gaming platforms, and / or combinations of such devices) may be provided in a manner equally suitable as the electronic device 8. As with the general electronic device 8 of the Fig. As discussed in Section 1, the handheld device 30 allows a user to connect to and communicate with the Internet or other networks, such as local or wide area networks. The handheld electronic device 30 can also communicate with other devices using short-range connections, such as Bluetooth and near-field communication. For example, the handheld device 30 could be a model of iPod®, iPad®, or iPhone®, available from Apple Inc. of Cupertino, California.

[0025] The handheld device 30 includes a display 10 in the form of an OLED display. The display 10 can be used to show a graphical user interface (GUI) 34, which allows a user to interact with the handheld device 30. The handheld electronic device 30 can also include various input and output (I / O) ports 12, which allow the handheld device 30 to be connected to external devices, such as a port that allows the transmission and reception of data or commands between the handheld device 30 and another electronic device.

[0026] In addition to the handheld device 30, such as the mobile phone shown, Fig. 2. An electronic device 8 may also take the form of a computer or other type of electronic device. Such computers may include computers that are generally portable (such as a laptop, notebook, and tablet computer), as well as computers that are generally used in one location (such as conventional desktop computers, workstations, and / or servers). In certain embodiments, the computer-shaped electronic device 8 may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, iPad®, or Mac Pro® available from Apple Inc. By way of example, an electronic device 8 in the form of a laptop computer 50 in Fig. Figure 3 illustrates an embodiment. The computer 50 shown includes a housing 52, a display 10 (such as an OLED display), input structures 14, and input / output ports 12.

[0027] In one embodiment, the input structures 14 (such as a keyboard and / or a touchpad) can be used to interact with the computer 50, for example, to start, control, or operate a GUI or applications running on the computer 50. For example, a keyboard and / or a touchpad can allow a user to navigate a user interface or an application interface displayed on the screen 10.

[0028] As shown, the electronic device 8 in the form of the computer 50 also includes various input and output ports 12 to allow the connection of additional devices. For example, the computer 50 may include an I / O port 12, such as a USB port or another port suitable for connecting to another electronic device, a projector, an additional display, etc. Additionally, the computer 50 may include a network connection, memory, and storage capabilities, as described in relation to Fig. As described in section 1. As a result, the computer can store and run a GUI and other applications.

[0029] With the preceding discussion in mind, it will be understood that an electronic device in the form of either a handheld device 30 or a computer 50 can be provided with an OLED display, such as the display 10. Such an OLED display can be used to display the respective operating system and application interfaces running on the electronic device 8 and / or to display data, images, or other optical outputs associated with an operation of the electronic device 8.

[0030] In embodiments where the electronic device 8 includes an OLED display, the display 10 can employ inorganic or organic light-emitting diodes (OLEDs). The OLED display can include a number of pixels composed of red, green, and blue subpixels. The OLED display can generate light in response to an electronic signal. Therefore, when bright images are displayed on the OLED display, relatively high power levels can be used to display the images.

[0031] With the preceding events in mind, illustrated Fig. 4 a data flow diagram 40 representing inputs that the ACL 28 can use to determine drive currents for each subpixel in the display 10, enabling the display 10 to conserve power while maintaining the integrity of the images displayed therein. In one embodiment, the ACL 28 can receive information relating to a type of application being reproduced by the display 10 (i.e., application type 42), an image to be displayed on the display 10 (i.e., image data 44), power consumption characteristics 45 of the display 10, ambient light measurements 46, and the like. Based on the application type 42, the image data 44, the power consumption characteristics 45, and / or the ambient light measurements 46, the ACL 28 can determine a drive current 48 for each subpixel in the display 10 during each frame of displayed data.As mentioned previously, the drive current 48 can be calculated for each subpixel, allowing the display 10 to conserve power while maintaining the quality of the displayed images. After determining the drive current 48 for each subpixel in the display 10 during each frame of displayed data, the ACL 28 can provide a corresponding drive current 48 to each subpixel in the display 10, thus enabling the display 10 to consume power efficiently. Further details describing how the ACL 28 can determine the drive current 48 for each subpixel in the display 10 during each frame of displayed data are given below with reference to the [references to be added]. Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. 10 provided.

[0032] Now referring to Fig. 5, the ACL 28 can employ a method 50 to determine the drive current 48 for each subpixel in the display 10 based on the application type 42 being displayed. At block 52, the ACL 28 can identify the application or program (i.e., the application type 42) being displayed by the display 10. In general, the ACL 28 can determine whether the application type 42 corresponds to an application that is also directed to display text for reading, images for viewing, or both. In some embodiments, different applications or programs may be operating simultaneously on a device, visible in different windows on the display. In this case, the ACL 28 can decide whether to apply different drive currents for the images displayed in each window or to apply a relatively uniform reduction in drive current across all windows.

[0033] At block 54, the ACL 28 can calculate the drive current 48, which can be used to drive each subpixel in the display 10 based on the application identified at block 52 (i.e., application type 42). In one embodiment, the calculated drive current can be optimized to save power consumption with respect to the display 10 while maintaining the integrity and quality of the images displayed on the display 10. For example, at block 52, the ACL 28 can identify an application type 42 corresponding to an application aimed at displaying text for reading. In this case, at block 54, the ACL 28 can calculate the drive currents 48 that can reduce the power consumed by the display 10 while maintaining the quality or readability of the text displayed on the display 10.Examples of text playback applications may include a word processing application, a spreadsheet application, an electronic mail (email) application, an electronic reading application, and similar applications.

[0034] In general, text display applications can show image data that includes black text against a white background. To generate a white background, a high amount of current can be supplied to each subpixel in the display 10 corresponding to the white background. To provide more energy-efficient displays, the ACL 28 at block 54 can calculate a reduced drive current for each subpixel in the display 10 based on the amount of white background being displayed. In this way, the overall white level of the background can be reduced while the black level of the text displayed in the display 10 remains relatively the same, since achieving black levels in the OLED subpixels consumes little or no power.Furthermore, reducing the overall white level of the background should not significantly impair the readability of the displayed text, as long as sufficient contrast exists between the text and the background due to the Bartleson-Breneman effect. The Bartleson-Breneman effect generally states that an image with very high contrast will actually appear brighter than an image with the same maximum brightness but lower contrast. In other words, if two displays show the same image, so that each has the same brightness level, the image with the higher contrast will appear brighter than the image with the lower contrast.

[0035] Against this background, the ACL 28 can utilize the Bartleson-Breneman effect for text rendering applications and can reduce the drive currents 48 supplied to the subpixels in the display 10. Since the contrast of black text on a white background in OLED displays will be high due to the high levels of black that OLEDs are capable of providing, reducing the overall white level of the white background will not significantly detract from a user's reading experience. In one embodiment, the ACL 28 can reduce the drive current supplied to the subpixels in the display 10 by a few percent or by an entire amount of the current specified by the respective application for the subpixels.For example, if the contrast between black text and a white background on an OLED display is 1000:1, then reducing the brightness of the white background (i.e., reducing the drive current supplied to the white background subpixels) by 20% (to 80% of the original brightness) can simply reduce the contrast between the black and white text to 800:1. In this way, the user's reading experience will not be significantly affected, as long as a sufficient amount of contrast exists between the displayed text and the background.By reducing the drive currents 48 supplied to the subpixels in the display 10 for text playback applications, the ACL 28 can maintain the readability of the displayed text based on the contrast between the displayed black text and the white background, while reducing the power consumed by the display 10.

[0036] Instead of reducing the drive current 48 to each subpixel in the display 10, in one embodiment the ACL 28 can reduce the drive current 48 supplied to the subpixels corresponding to the white background. That is, the ACL 28 can reduce the drive current 48 supplied to each subpixel corresponding to a pixel displaying a white color, while maintaining the drive currents 48 for the subpixels not used to display a white color.

[0037] As previously mentioned, when determining the drive current 48, the ACL 48 can reduce the amount of current supplied to the subpixels in the display 10 by a few percent or by an entire amount of current specified by the application. In one embodiment, the ACL 28 can reduce the drive currents 48 supplied to subpixels that have a brightness level greater than any brightness level limit. For example, if the brightness level limit is 80% of the maximum brightness value, the ACL 28 can reduce the drive currents 48 of the respective subpixels that have a brightness above 80%.In one embodiment, the ACL 28 can reduce the drive currents 48 supplied to these respective subpixels by 20% to 80% or by 60% to 80%, while maintaining the drive currents 48 supplied to the subpixels with a brightness below 80%. In this way, the ACL 28 can achieve a more significant power saving in the display 10 while maintaining a certain level of image quality displayed on the display 10.

[0038] Instead of reducing the drive currents 48 of the respective subpixels that have a brightness above the brightness level limit by a certain percentage, the ACL 28 can reduce the drive currents 48 supplied to each respective subpixel that has a brightness above the brightness level limit, so that the respective subpixel has a brightness level that corresponds to the brightness level limit. In any case, after calculating the drive currents 48 for each subpixel in the display 10, the ACL 28 can send the calculated drive currents 48 to each subpixel in the display 10 at block 56.

[0039] Referring back to Block 52, if the application type 42 is aimed at displaying image data 44 that includes colorful photos or videos, the ACL 28 at Block 54 cannot reduce the drive currents 48 to preserve the quality of the displayed image data 44. As a result, the ACL 28 can provide the drive currents 48 as specified by the respective application for each subpixel in the display 10. Alternatively, the ACL 28 can reduce the drive currents 48 applied to each subpixel in the display 10 by a small percentage (e.g., less than 10%) so that the image quality of the displayed image is preserved. In this way, the ACL 28 can limit or eliminate the amount of current reduction applied to the calculated drive currents 48 in Block 54 for applications where accurate colors and brightness are desirable.This means that the ACL 28 can significantly reduce the drive currents 48 for application types 42 that inherently consume a lot of power but display images that are not particularly colorful or detailed. Accordingly, the ACL 28 can enable the display 10 to become more power-efficient for application types 42 that do not display particularly colorful or detailed images, while maintaining the image quality of the images displayed in the display 10 for those application types 42 that display colorful and detailed images.

[0040] In one embodiment, the ACL 28 can reduce the drive currents 48 supplied to the display 10 for application types 42 in which images are displayed, according to a method 58 described in Fig. 6 is described. With reference to Fig. At block 60, ACL 28 can receive image data 44 containing one or more images to be displayed on the display 10. At block 62, ACL 28 can analyze the image data 44 and identify one or more portions within the displayed image data 44 that have substantially similar properties, such as pixels with substantially similar brightness and color values. For example, portions of the image data 44 that have substantially similar brightness or color values ​​may include portions of the image data 44 that contain "white" pixels. White pixels may include pixels that meet or exceed a certain minimum brightness value and have a set of color coordinates that lies within a region defined as "white".In addition to white pixels, portions of the image data 44 that have substantially similar brightness or color values ​​may include portions of the image data 44 that contain the same bright and pure color.

[0041] In one embodiment, the ACL 28 can identify the portions of the image data 44 that have substantially similar properties by comparing the brightness and / or color coordinates of a given pixel with its neighboring pixels. Pixels directly adjacent to the respective pixel can be categorized as part of a first level of proximity pixels. Similarly, pixels immediately adjacent to the pixels of the first level can be categorized as part of a second level of proximity pixels. The ACL 28 can identify the portion of the image data 44 that has substantially similar properties based on whether the portion of the image data 44 includes a number of pixels or levels of proximity pixels that have substantially similar brightness and / or color coordinates.For example, the ACL 28 can identify portions of the image data 44 as being essentially the same as the respective pixel for areas of the image data 44 that contain pixels in which the brightness and color coordinates of the pixels differ by up to four levels.

[0042] After identifying the portions of the image data 44 that have substantially similar properties, the ACL 28 can reduce the drive currents 48 supplied to the subpixels corresponding to the portions of the image data 44 identified at block 60 at block 64. In this way, the ACL 28 can reduce the brightness in portions of the image data 44 that can be used for background purposes, while maintaining the brightness of the images represented in the image data 44. An example of the effects of reducing the brightness in the portions of the image data 44 that are part of the background of the image data 44 is shown in Fig. 7 illustrates.

[0043] With reference to Fig. Figure 63, shown in Figure 7, illustrates the results of using a conventional ACL control to uniformly reduce the overall power of the image data 44 by dimming both the white and color components of the image data 44. From an energy-saving point of view, reducing the white brightness provides significant power benefits, whereas reducing the image brightness provides only minor power benefits. Furthermore, reducing the image brightness decreases the quality of the colors displayed in the image. Generally, users may not be affected by the brightness of the background or frame, but will be very sensitive to a reduction in the brightness of the colored image.

[0044] Against this background, the ACL 28 can achieve significant power savings while simultaneously providing accurate brightness and color coordinates for the displayed images by reducing the brightness only in the background portion of the image data 44, as shown in Figure 65. Fig. 7 illustrates. With reference back to Fig. 5, after determining the drive currents 48 for the identified portions of the image data 44, the calculated drive currents can be sent to the display 10 at block 56 of the ACL 28.

[0045] In addition to modifying the drive currents 48 based on the application type 42 or the image data 44 displayed on the screen 10, the ACL 28 can also modify the drive currents 48 supplied to the screen 10 based on the power consumption characteristics 45 of the screen 10, as described in procedure 66 of the Fig. 8 shown. Now with reference to Fig. At block 68, ACL 28 can determine the power consumption characteristics 45 for the display 10. At block 70, ACL 28 can determine whether the power consumption characteristics 45 exceed a limit. If the power consumption characteristics 45 exceed the limit, ACL 28 can proceed to block 72 and reduce the drive currents 48 to be supplied to the display. However, if the power consumption characteristics 45 do not exceed the limit, ACL 28 can proceed to block 74 and maintain the drive currents 48 to be supplied to the display 10.

[0046] In one embodiment, the power consumption characteristics 45 can be determined based on the brightness and color properties displayed in each pixel of the display 10. In certain devices, such as an OLED display, the power consumption characteristics 45 vary for generating different colors for each color because each individual pixel in an OLED display displays its own color. For example, a blue pixel in an OLED display is generally less power-efficient than a green pixel, even if both of these pixels have the same brightness. The difference in efficiency for each color generally depends on the exact material composition and structure of the OLED subpixels (i.e., the OLED layers).Similarly, the relative efficiency for white OLEDs with color filters generally depends on the color subpixels due to the OLED material, the OLED design properties, and the optical properties of the color filters. Therefore, by considering both the brightness and color properties for each pixel in the display 10, ACL 28 can more accurately determine the power consumption characteristics 45 for the display 10. A method 75, which describes how the power consumption characteristics 45 can be determined using both the brightness and color properties for each pixel in the display 10, is described in more detail below with reference to [reference missing]. Fig. 9 described.

[0047] With reference to Fig. 9. At block 76, the ACL 28 can receive red, green, and blue color data (RGB data) for each pixel in the display 10. At block 78, the ACL 28 can convert the RGB data into the International Commission on Illumination (CIE) 1976 (L*, u*, v*) color space or L*u*v* coordinates. After converting the RGB data for each pixel into L*u*v* coordinates, at block 80 the ACL 28 can adjust the brightness (L*) value by a factor (P). u*v* ) scales, which depends on the corresponding u*v* value. The scaling factor can be used to more accurately characterize the amount of power consumed by each pixel based on the color that the pixel displays.

[0048] For block 82, the ACL 28 can measure the scaled brightness value (L* × P). u*v* Sum 10 for each pixel in the display. Referring back to block 70 in Fig. In block 8, ACL 28 can then compare the sum (i.e., the power consumption value) with a limit. If the sum is greater than the limit, ACL 28 can proceed to block 72 and reduce the drive currents 48 supplied to each subpixel in the display 10, as described previously. Alternatively, if the sum is not greater than the limit, ACL 28 can proceed to block 74 and maintain the drive currents 48 as specified by the relevant application.

[0049] In one embodiment, ACL 28 can omit block 78 and apply the scaling factors for each pixel at block 80 to each corresponding subpixel. This means that the individual RGB values ​​for each pixel can be multiplied by an appropriate scaling factor (e.g., P). R , P G , P BThe values ​​of the values ​​that can be stored in a lookup table, and the resulting products, can be summed to determine the power consumption characteristics 45 of the display 10. Therefore, the power consumption characteristics 45 for the display 10 can be calculated by summing the values ​​of R × P. R , G × P G and B × P B for all of the subpixels in the display 10. The scaling factor (P R , P G , P B ) can represent a value proportional to the amount of power that would be consumed to drive a particular subpixel to its respective red, green, or blue value. After summing the values ​​of R × P R , G × P G and B × P B For all subpixels in display 10, ACL 28 can proceed to block 70 of procedure 66 and can determine whether the sum is greater than the limit.

[0050] If the sum is greater than the limit, ACL 28 at block 72 can reduce the drive currents 48 supplied to each respective subpixel so that each pixel can have RGB values ​​at a threshold. For example, ACL 28 can compare the red, green, and blue digital levels (e.g., 0 to 255 for an 8-bit subpixel) for corresponding red, green, and blue subpixels in each pixel in the portion of image data 44 with the threshold. If the red, green, or blue subpixel in each pixel of the portion of image data 44 has a digital level above the threshold, ACL 28 can reduce the drive currents 48 supplied to each of the corresponding subpixels to the threshold.In one embodiment, the ACL 28 can reduce the drive currents 48, as previously described, only if each of the three subpixels in the respective pixel is below the threshold to prevent any change in the colored background colors.

[0051] In certain situations, a change in color in a portion of the display 10 can cause the total to exceed the limit at block 70 and may cause the ACL 28 to reduce the drive currents 48 supplied to the display 10 at block 72. For example, if a large portion of the display 10 changes from green to blue, and because blue emission consumes more power than green emission, the power consumption characteristics 45 for the display 10 will increase due to the increased power consumption corresponding to the blue pixels in the OLED display. In this case, if a different portion of the same display 10 is held constant while the other portion changes color from green to blue, the color change could then lead to an overall reduction in the drive currents 48 applied to the entire display 10, which will change the portion of the display 10 that is intended to remain constant.As a result, a user viewing the images displayed on Display 10 may be disappointed with the image quality. For example, if most of the content displayed on Display 10 changes from a dark image to a bright image, the user is unlikely to notice a reduction in the brightness of the bright image as a power-saving measure. However, if only part of an image changes brightness while other parts remain unchanged, the user may be bothered by any significant change in the brightness of the portion of the image intended to remain constant. In this case, ACL 28 can override the procedure 66 described earlier and maintain the applied current at a previous level until a significant change in the displayed content occurs.Alternatively, the ACL 28 can implement the current reduction gradually over a period of time, so that the user does not notice a significant change in image brightness. For example, the current reduction can occur in a series of small steps over a duration of 1 to 10 seconds, making the change barely perceptible to the viewer.

[0052] At block 71, the ACL 28 can execute an additional procedure that determines whether a change in the colors or color intensities of the images displayed on the display 10 exceeds a certain threshold. If the colors of the image do indeed change, such that the amount of change exceeds the threshold, the ACL 28 can proceed to block 74 and maintain the drive currents 48 as specified. However, if the colors of the images do not change, such that the amount of change does not exceed the threshold, the ACL 28 can proceed to block 72 and reduce the drive currents 48 as previously described. In this way, the ACL 28 can avoid changing the drive currents supplied to each subpixel in the display 10 if the power consumption value becomes greater than the limit due to a color change of a portion of the display 10, but not due to a change in the brightness of the display 10.

[0053] Although Method 75 has been described for OLED displays equipped with RGB color filters, it should be understood that in certain embodiments, Method 75 can also be performed for OLED displays equipped with RGBW color filters. In this case, after ACL 28 receives the RGB data for each pixel in the display 10 at block 76, ACL 28 can convert the RGB data to RGBW data, and the remaining steps of Method 75 can be performed based on the RGBW data.

[0054] For displays with a high pixel count, Method 75 can involve a significant amount of processing time and power. To reduce the amount of processing time and power used to execute Method 75, ACL 28 can randomly sample a subset of all pixels in the display 10 and determine an estimate of the brightness of the entire display 10 based on the sample. For example, illustrates Fig. ACL 28 describes a method for determining an estimate of the brightness of the display using a sampling algorithm. To improve accuracy, the ACL 28 can divide the display into a number of fixed regions along the display area. The ACL 28 can then randomly sample one or more pixels in each fixed region to better ensure that the current reduction is representative of the images displayed across the entire screen. For example, the display can be divided into 64 rectangles of uniform height and uniform width, either equal or different, distributed uniformly along the display. The ACL 28 can then perform pixel sampling within each of these specific rectangles.

[0055] Now with reference to Fig. At block 86, ACL 28 can sample a fraction or subset of the image data 44 to be displayed on the display 10. At block 88, the ACL can convert the sampled image data into a linear intensity scale, for example, by applying a degamma function. Using this linear intensity scale, ACL 28 can determine statistics for the relative intensity of each subpixel in the sampled image data at block 90. ​​At block 92, ACL 28 can then use these statistics to calculate the amount of power consumed by the display 10. ACL 28 can then compare this calculated power value with the limit, as described in block 70, and proceed to block 72, block 71, or block 74, depending on whether the calculated power value is greater than the limit.

[0056] For each of the procedures described above (i.e., procedures 50, 58, 75, or 84), if a portion of the display 10 changes rapidly between frames of data, the ACL 28 may supply rapidly fluctuating drive currents 48 to the pixels of the display 10, causing a flickering effect or other optical artifacts to be displayed on the display 10. To prevent these types of optical artifacts, the procedures described above can be modified so that the ACL 28 is not allowed to change the drive currents 48 more than once during a given time period. For example, in procedure 66, the ACL 28 may not be allowed to change the drive currents 48 at block 72 more than once within a 5-second period.

[0057] With reference back to Fig. 4. In addition to the application type 42, the image data 44, and the power consumption characteristics 45, the ACL 28 can use the ambient light measurements 46 to determine the drive currents 48 for each subpixel in the display 10. The ambient light measurements 46 can be acquired by the light sensors 22, as previously described, and can indicate the total illuminance level acting on the light sensors 22. In general, the ambient light measurements 46 can indicate whether the device is located outdoors or indoors. In one embodiment, the ACL 28 can adjust the drive currents 48 supplied to the display 10 based on the ambient light measurements 46 according to a method 96, which is described below with reference to Fig. 11 is described.

[0058] At block 98, the ACL 28 can receive ambient light measurements 46 from the light sensors 22. At block 100, the ACL 28 can receive data relating to images to be displayed on the screen 10. At block 102, the ACL 28 can calculate the drive currents 48 for each subpixel in the screen 10 based on the ambient light measurements 46. In one embodiment, if the ambient light measurements 46 exceed a certain threshold, the ACL 28 can reduce the drive currents 48 supplied to the screen 10. In this way, the ACL 28 can implement a different set of drive currents 48 for high ambient light measurements 46 compared to lower ambient light measurements 46.

[0059] In one embodiment, the ACL 28 can calculate the drive currents 48 based on the application type 42, the image data 44, the power consumption characteristics 45, the ambient light measurements 46, or a combination of these inputs. For example, if the ACL 28 receives ambient light measurements 46 that are greater than the threshold (e.g., outdoor use) and an application type 42 that corresponds to a text display application, the ACL 28 can increase the brightness of the entire display 10 to make it easier for the user to view the text displayed on the display 10. However, if the ACL 28 receives ambient light measurements 46 that are greater than the threshold (e.g., outdoor use) and an application type 42 that corresponds to an image display application, the ACL 28 can supply drive currents 46 to the display 10 based on the amount of white color supplied to the display 10.Here, the ACL 28 reduces the drive currents 48 by a larger amount for images that have a large proportion of white color displayed on the screen 10, compared to images that have a small proportion of white displayed on the screen 10.

[0060] By implementing the methods described herein, the ACL 28 can provide greater power savings for the display 10 and can prevent the generation of high levels of heat in the display 10, which can damage various components within the display 10. Furthermore, a user can experience a more satisfactory viewing experience on the display 10 while the display 10 employs various power-saving techniques.

[0061] The specific embodiments described above have been shown as examples, and it should be understood that these embodiments are open to various modifications and alternative forms. It should further be understood that the claims are not intended to be limited to the specific disclosed forms, but rather are intended to encompass all modifications, equivalents, and alternatives that fall within the spirit and scope of this disclosure.

Claims

[1] Procedure (58) encompassing: Receiving drive current values ​​linked to subpixels in a display (10); Identify (62) at least one proportion of image data (44) comprising a plurality of pixels with substantially uniform brightness and substantially uniform color coordinates; Reducing (64) at least some of the drive current values ​​corresponding to the proportion of image data (44); Do not reduce at least some of the drive current values ​​if the portion of the image data (44) does not include substantially uniform brightness and substantially uniform color coordinates; and Supplying the subpixels with the drive currents (48) that correspond to the drive current values. [2] Method (58) according to claim 1, wherein reducing the at least some of the drive current values ​​comprises reducing the at least some of the drive current values, wherein the application method (42) corresponds to a text playback application. [3] Method (58) according to claim 2, wherein at least some of the drive current values ​​are reduced by a percentage between 20% and 80%. [4] Method (58) according to claim 2, wherein at least some of the drive current values ​​are reduced at least partially on the basis of an amount of white color displayed on the screen (10). [5] Method (58) according to claim 2, wherein at least some of the drive current values ​​correspond to a proportion of the subpixels that represent a white color. [6] Method (58) according to claim 1, wherein at least some of the drive current values ​​correspond to a proportion of the subpixels, each subpixel in the proportion having a brightness above a limit. [7] Method (58) according to claim 6, wherein each drive current value is reduced to at least some of the drive current values ​​in order to cause the brightness of the respective subpixels to be reduced to the limit. [8] Method (58) according to claim 1, wherein the reduction (64) of at least some of the drive current values ​​comprises reducing the drive current values ​​corresponding to the subpixels of a white color. [9] Method (58) according to claim 1, comprising: Receiving power consumption data corresponding to the display (10); and Reducing (64) at least some of the drive current values ​​if the power consumption data exceeds a limit. [10] Method (58) according to claim 1, comprising: Receiving a measurement (46) of ambient light at the display (10); and reducing at least some of the drive current values ​​when the measurement (46) of ambient light is greater than a threshold. [11] System, encompassing: an automatic current limiting, ACL control (28) which is configured to: to receive drive current values ​​that are linked to subpixels in a display device (10); to receive an estimate corresponding to the power consumption of the display device (10), wherein the estimate is determined by: Converting red, green and blue (RBG) data for each pixel from a multitude of pixels in the image data into L*u*v* coordinates; Scaling each L* value for each pixel by a factor at least partially based on a respective u*v* value; and Summing up the scaled L* values ​​for each pixel; Reducing at least some of the drive current values, at least in part, based on estimation; and Sending the drive currents, corresponding to the drive current values, to the subpixels. [12] System according to claim 11, wherein the ACL control (28) is configured to reduce at least some of the drive currents when the summed, scaled L* value is greater than a threshold. [13] System according to claim 11, wherein at least some of the drive currents are reduced by a percentage of 20% and 80%.

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