PATENT DOCUMENT

Publication Number: US-11348555-B2
Application Number: US-202117216376-A
Country: US
Kind Code: B2

Title: Display with localized brightness adjustment capabilities

Abstract:
An electronic device may have a display with an array of pixels. The device may have an array of components such as an array of light sensors for capturing fingerprints of a user through an array of corresponding transparent windows in the display. A capacitive touch sensor, proximity sensor, force sensor, or other sensor may be used by control circuitry in the device to monitor for the presence of a user&#39;s finger over the array of light sensors. In response, the control circuitry can direct the display to illuminate a subset of the pixels, thereby illuminating the user&#39;s finger and causing reflected light from the finger to illuminate the array of light sensors for a fingerprint capture operation. The display may have display driver circuitry that facilitates the momentary illumination of the subset of pixels with uniform flash data while image data is displayed in other portions of the display.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 an array of display pixels; 
 display driver circuitry configured to direct pixels in a first region of the array to display image data while directing pixels in a second region of the array to display external object sensing data that is different than the image data; and 
 a sensor at least partially covered by at least some of the pixels in the second region of the array and configured to measure an illumination of an external object using the external object sensing data. 
 
     
     
       2. The electronic device of  claim 1 , wherein the sensor comprises a fingerprint sensor. 
     
     
       3. The electronic device of  claim 1 , wherein the external object sensing data comprises flash data. 
     
     
       4. The electronic device of  claim 1 , wherein the external object sensing data comprises uniform flash data. 
     
     
       5. The electronic device of  claim 1 , wherein the external object sensing data comprises non-uniform flash data. 
     
     
       6. An electronic device comprising:
 an array of display pixels; and 
 display driver circuitry configured to direct pixels in a non-flash region of the array to display image data while directing pixels in a flash region of the array to display non-image data for less than a second. 
 
     
     
       7. The electronic device of  claim 6 , further comprising:
 a sensor at least partially overlapped by the flash region. 
 
     
     
       8. The electronic device of  claim 7 , wherein the sensor is configured to receive signals through a transparent region among the pixels in the flash region. 
     
     
       9. The electronic device of  claim 7 , wherein the sensor comprises a fingerprint sensor. 
     
     
       10. The electronic device of  claim 7 , wherein the flash region has a rectangular shape in a predetermined location on the electronic device. 
     
     
       11. The electronic device of  claim 7 , wherein the flash region has a shape with curved edges in a predetermined location on the electronic device. 
     
     
       12. The electronic device of  claim 6 , wherein the non-image data comprises uniform or non-uniform flash data. 
     
     
       13. An electronic device comprising:
 display pixels; and 
 display driver circuitry configured to:
 direct a first portion of the display pixels to operate in an image display mode; and 
 direct a second portion of the display pixels to operate in a sensing mode different than the image display mode, wherein the second portion of the display pixels comprise a plurality of adjacent pixels configured to present object sensing data during the sensing mode. 
 
 
     
     
       14. The electronic device of  claim 13 , further comprising:
 a sensor configured to receive signals through a region among the second portion of the display pixels. 
 
     
     
       15. The electronic device of  claim 14 , wherein the sensor comprises a fingerprint sensor. 
     
     
       16. The electronic device of  claim 13 , wherein:
 the first portion of the display pixels are configured to present normal image data when operating in the image display mode. 
 
     
     
       17. The electronic device of  claim 16 , wherein the object sensing data comprises uniform or non-uniform flash data. 
     
     
       18. The electronic device of  claim 13 , wherein the display driver circuitry is further configured to direct the second portion of the display pixels to operate in the image display mode to present normal image data.

Description:
This application is a continuation of patent application Ser. No. 16/584,807, filed Sep. 26, 2019, which is a continuation of patent application Ser. No. 16/222,492, filed Dec. 17, 2018, now U.S. Pat. No. 10,467,985, which is a continuation of patent application Ser. No. 15/257,448, filed Sep. 6, 2016, now U.S. Pat. No. 10,157,590, which claims the benefit of provisional patent application No. 62/267,537, filed Dec. 15, 2015, all of which are incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to electronic devices with displays. 
     Electronic devices often include displays. Displays such as organic light-emitting diode displays have pixels with light-emitting diodes. During normal operation, the pixels are illuminated to display images for a user. 
     In some situations, it may be desirable to provide non-image illumination with the pixels. If care is not taken, this illumination will not have desired attributes. 
     It would therefore be desirable to be able to provide improved electronic devices and display arrangements for accommodating the use of pixels to provide non-image illumination. 
     SUMMARY 
     An electronic device may have a display. The display may have an array of pixels such as an array of pixels with organic light-emitting diodes or other light-emitting diodes. The device may have an array of electrical components mounted under the display. The electrical components may be an array of light sensors for capturing fingerprints from a user or for gathering information on other external objects. The light sensors in the array may gather light readings through an array of corresponding transparent windows in the display. 
     A capacitive touch sensor, proximity sensor, light detector, strain gauge sensor or other force sensor, or other sensor may be used by control circuitry in the device to monitor for the presence of a user&#39;s finger or other object over the array of light sensors. In response to detecting the user&#39;s finger, the control circuitry can direct the display to illuminate a portion of the display or all of the display with uniform light. For example, in a configuration in which a light sensor array occupies a portion of a display, a subset of the pixels that overlaps the light sensor may be illuminated. 
     The illuminated subset of pixels can produce a flash of illumination or may otherwise be adjusted in brightness independently from pixels in the rest of the display. The flash may be relatively brief. For example, the length of the flash may be equal to one frame time (e.g., 1/60 s in a display in which the rate at which image frames are displayed is 60 Hz). The flash may illuminate a user&#39;s finger that is adjacent to the subset of pixels and the light sensor array. Reflected light from the user&#39;s finger may illuminate the array of light sensors for a fingerprint capture operation. Illuminating the light sensors with a flash of light from subset of the pixels overlapping the light sensor array (i.e., a flash region) may help ensure that fingerprint capture operations are performed satisfactorily. 
     The display may have display driver circuitry that facilitates the momentary illumination of the subset of pixels with uniform flash data while image data or other suitable data is displayed in other portions of the display. The display driver circuitry may have multiplexer circuitry that selectively routes either image data or flash data to a set of pixels in a fixed flash region on the display or may have multiplexer circuitry that can be dynamically configured to place the flash region at a desired location on the display. 
     Further features will be more apparent from the accompanying drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device having a display in accordance with an embodiment. 
         FIG. 2  is a top view of an illustrative display in an electronic device in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of a display with an array of electrical components in accordance with an embodiment. 
         FIG. 4  is a top view of an illustrative display with a region that is being used to provide flash illumination in accordance with an embodiment. 
         FIGS. 5 and 6  are diagrams of illustrative display driver circuitry in accordance with an embodiment. 
         FIG. 7  is a timing diagram showing how image data may be loaded into a display in accordance with an embodiment. 
         FIG. 8  is a timing diagram showing how flash data may be loaded into a display so that a region of the display produces flash illumination in accordance with an embodiment. 
         FIG. 9  is a flow chart of illustrative operations involved in loading flash data into a display so that a region of the display produces flash illumination in accordance with an embodiment. 
         FIG. 10  is a diagram of illustrative display driver circuitry that may be configured to place a flash region in a desired location on a display in accordance with an embodiment. 
         FIG. 11  is a diagram of illustrative display driver circuitry of the type that may be used to adjust display brightness in a local region of a display independently from the rest of the display in accordance with an embodiment. 
         FIG. 12  is a graph in analog pixel voltage has been plotted as a function of digital data value for a local display region and other portions of a display with driver circuitry of the type shown in  FIG. 11  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with a display is shown in  FIG. 1 . As shown in  FIG. 1 , electronic device  10  may have control circuitry  16 . Control circuitry  16  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  16  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Input-output circuitry in device  10  such as input-output devices  12  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  12  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors (e.g., light-based proximity sensors such as infrared proximity sensors, capacitive touch sensors, force sensors such as capacitive force sensors and strain gauge force sensors, light detectors, etc.), light-emitting diodes and other status indicators, data ports, and other electrical components. A user can control the operation of device  10  by supplying commands through input-output devices  12  and may receive status information and other output from device  10  using the output resources of input-output devices  12 . 
     Input-output devices  12  may include one or more displays such as display  14 . Display  14  may be a touch screen display that includes a touch sensor for gathering touch input from a user or display  14  may be insensitive to touch. A touch sensor for display  14  may be based on an array of capacitive touch sensor electrodes, acoustic touch sensor structures, resistive touch components, force-based touch sensor structures, a light-based touch sensor, or other suitable touch sensor arrangements. 
     Control circuitry  16  may be used to run software on device  10  such as operating system code and applications. During operation of device  10 , the software running on control circuitry  16  may display images on display  14  using an array of pixels in display  14 . 
     When it is desired to produce illumination with the pixels of display  14 , the software running on control circuitry  16  may use display  14  to illuminate a region of the pixels on display  14 . The region may, for example, be a rectangular portion of display  14  or a region with another shape that serves as flash illumination for a photograph, flash illumination for a fingerprint capture operation, illumination for document scanning operations, or illumination for other operations in which an object external to device  10  is to be illuminated. 
     The illuminated region, which may sometimes be referred to as a flash region or flash area, may be white or may have other colors. The color of the flash area (e.g., the color temperature of a white flash area) may be adjusted to provide illumination with desired color characteristics (e.g., to satisfy aesthetic requirements, to enhance the warmth of a photograph, to ensure that a fingerprint capture operation is performed satisfactorily, etc.). The brightness of the flash area may also be adjusted. Uniform flash illumination is generally appropriate, but non-uniform patterns of illumination may be provided, if desired. 
     Device  10  may be a tablet computer, laptop computer, a desktop computer, a display, a cellular telephone, a media player, a wristwatch device or other wearable electronic equipment, or other suitable electronic device. 
     Display  14  may be an organic light-emitting diode display or may be a display based on other types of display technology. Configurations in which display  14  is an organic light-emitting diode display are sometimes described herein as an example. This is, however, merely illustrative. Any suitable type of display may be used, if desired. 
     Display  14  may have a rectangular shape (i.e., display  14  may have a rectangular footprint and a rectangular peripheral edge that runs around the rectangular footprint) or may have other suitable shapes. Display  14  may be planar or may have a curved profile. 
     A top view of a portion of display  14  is shown in  FIG. 2 . As shown in  FIG. 2 , display  14  may have an array of pixels  22  formed on substrate  36 . Substrate  36  may be formed from glass, metal, plastic, ceramic, or other substrate materials. Pixels  22  may receive data signals over signal paths such as data lines D and may receive one or more control signals over control signal paths such as horizontal control lines G (sometimes referred to as gate lines, scan lines, emission control lines, etc.). There may be any suitable number of rows and columns of pixels  22  in display  14  (e.g., tens or more, hundreds or more, or thousands or more). Each pixel  22  may have a light-emitting diode  26  that emits light  24  under the control of a pixel circuit formed from thin-film transistor circuitry such as thin-film transistors  28  and thin-film capacitors). Thin-film transistors  28  may be polysilicon thin-film transistors, semiconducting-oxide thin-film transistors such as indium gallium zinc oxide transistors, or thin-film transistors formed from other semiconductors. Pixels  22  may contain light-emitting diodes of different colors (e.g., red, green, and blue diodes for red, green, and blue pixels, respectively) to provide display  14  with the ability to display color images. 
     Display driver circuitry may be used to control the operation of pixels  22 . The display driver circuitry may be formed from integrated circuits, thin-film transistor circuits, or other suitable circuitry. Display driver circuitry  30  of  FIG. 2  may contain communications circuitry for communicating with system control circuitry such as control circuitry  16  of  FIG. 1  over path  32 . Path  32  may be formed from traces on a flexible printed circuit or other cable. During operation, the control circuitry (e.g., control circuitry  16  of  FIG. 1 ) may supply circuitry  30  with information on images to be displayed on display  14 . 
     To display the images on display pixels  22 , display driver circuitry  30  may supply image data to data lines D while issuing clock signals and other control signals to supporting display driver circuitry such as gate driver circuitry  34  over path  38 . Gate driver circuitry  34  can assert appropriate gate signals (e.g., gate signals in successive rows may be asserted in sequence to load each frame of data). If desired, circuitry  30  may also supply clock signals and other control signals to gate driver circuitry on an opposing edge of display  14 . 
     Gate driver circuitry  34  (sometimes referred to as horizontal control line control circuitry) may be implemented as part of an integrated circuit and/or may be implemented using thin-film transistor circuitry. Horizontal control lines G in display  14  may carry gate line signals (e.g., scan line signals, emission enable control signals, and other horizontal control signals) for controlling the pixels of each row. There may be any suitable number of horizontal control signals per row of pixels  22  (e.g., one or more, two or more, three or more, four or more, etc.). 
     It may be desirable to incorporate electrical components into display  14  and/or device  10 . As shown in  FIG. 3 , for example, electrical components  84  may be incorporated into device  10  under pixels  22 . Components  84  may be discrete components or may be formed as part of a common integrated circuit or other shared component. Components  84  may, as an example, be formed as part of device  82  (e.g., an integrated circuit) or may be mounted on a printed circuit substrate. 
     Electrical components  84  may be audio components (e.g., microphones, speakers, etc.), radio-frequency components, haptic components (e.g., piezoelectric structures, vibrators, etc.), may be capacitive touch sensor components or other touch sensor structures, may be temperature sensors, pressure sensors, magnetic sensors, or other sensors, or may be any other suitable type of electrical component. With one suitable arrangement, which may sometimes be described herein as an example, electrical components  84  may be light-based components (e.g., components that emit and/or detect visible light, infrared light, and/or ultraviolet light). 
     Light-based components  84  may emit and/or detect light that passes through transparent windows  76  in display  14 . Windows  76  may be formed in regions located between pixels  22  and may include transparent materials (e.g., clear plastic, glass, etc.) and/or holes (e.g., air-filled openings or openings filled with transparent material that pass partly or fully through substrate  36  and other display layers  74  of display  14  such as thin-film layers forming thin-film transistors and organic light-emitting diodes). 
     There may be a window  76  between each pair of pixels  22  or, more preferably, blocks of pixels  22  (e.g., blocks of tens, hundreds, or thousands of pixels) may be associated with windows  76  and electrical components  84 . 
     Examples of light-based components  84  that emit light include light-emitting diodes (e.g., organic light-emitting diodes, discrete crystalline light-emitting diode dies, etc.), lasers, and lamps. Examples of light-based components that detect light include light detectors such as photodiodes and phototransistors. Some components may, if desired, include both light emitters and detectors. For example, components  84  may emit infrared light and may include light detector structures for detecting a portion of the emitted light that has reflected from nearby objects such as object  86 . Components of this type may be used to implement a proximity sensor. In configurations in which components  84  include light sensors, an array of components  84  may form a light-based fingerprint sensor (e.g., when object  86  is the finger of a user) or other light-based sensor (e.g., a light sensor that detects the presence or absence of a finger or other external object by determining when components  84  have been shadowed by object  86  so that ambient light at components  84  is reduced). The presence of a user&#39;s finger or other external object  86  over a given portion of display  14  (e.g., over a region that includes an array of components  84 ) may, if desired, be detected using a touch sensor formed from capacitive touch sensor electrodes in display  14 , a force sensor (e.g., a capacitive force sensor that measures force by detecting capacitance changes as a user presses on a portion of display  14 , a strain gauge that measures force on display  14 , or other force sensing structures), a light detector (e.g., a light detector that detects the user&#39;s finger by measuring shadowing of ambient light), an infrared proximity sensor or array of infrared proximity sensors or other light-based sensors, etc. 
     If desired, light-based sensors such as these may sense fingerprints while object  86  is illuminated with light  24  from one or more of pixels  22 . This light may be produced by placing a region of display  14  (i.e., a “flash region”) in a flash mode. When operating normally, the pixels of the flash region may be used in displaying images for a user on display  14 . In the flash mode, pixels  22  may produce a block of solid white light or other illumination to briefly illuminate object  86 . Pixels  22  may, for example, produce a flash of white light that lasts for the duration of one frame of image data on display  14 . The flash region of display  14  may be aligned with a portion of display  14  that includes an array of windows  76  (as an example). Finger sensing components such as a force sensor, capacitive touch sensor, proximity sensor, or other detector may also overlap this portion of display  14  to detect when a user&#39;s finger is present and flash illumination is appropriate. 
     An illustrative display with a flash region is shown in  FIG. 4 . In the illustrative configuration of  FIG. 4 , display  14  has an array of pixels  22  that receive data over vertical data lines D 0  . . . DF while receiving control signals over horizontal gate lines G 0  . . . GF. Flash region  100  may cover some or all of display  14  and may have a rectangular shape, an oval shape, a shape with curved edges, a shape with straight edges, a shape with a combination of curved and straight edges, a shape with multiple discrete parts that are separated from each other by intervening pixels that are actively displaying image data, or any other suitable shape. In the example of  FIG. 4 , flash region  100  has a rectangular shape and is located near to the lower edge of display  14 . This is merely illustrative. Region  100  may have any suitable shape. The portions of display  14  that are not included in flash region  100  may sometimes be referred to as forming a non-flash region on display  14 . 
     During normal image data loading operations, data lines D 0  . . . DF may be used to load image data into display  14 . Rows of pixels may be loaded in sequence by issuing control signals over gate lines G 0  . . . GF. 
     Data line voltages suitable for operating the pixels of region  100  in flash mode may be supplied to the pixels of region  100  using data lines DN . . . DM while issuing a sequence of control signals on gate lines GK . . . GL. 
     Illustrative display driver circuitry  100  (see, e.g., the display driver circuitry of FIG.  2 ) for display  14  is shown in  FIG. 5 . As shown in  FIG. 5 , circuitry  100  may include a brightness digital-to-analog converter (DAC) such as converter  102 . Converter  102  may receive a digital user brightness setting from input  104 . The user brightness setting may, for example, be an overall level of display brightness for display  14  that a user of device  10  has supplied to device  10  using input-output devices  12  and/or that control circuitry  16  has determined based on other input such as input from an ambient light sensor. Converter  102  may supply a voltage Vreg 2  at output  106  corresponding to the display brightness setting received at input  104 . The value of Vreg 2  may, for example, be relatively high when the brightness setting is high and may be relatively low when the brightness setting is low. 
     Gamma block  108  may receive voltage Vreg 2  from output  106  and may generate a set of voltages V 255  . . . V 0  at outputs  112  (e.g., using a voltage divider formed from a resistor tree and other circuitry). The values of V 225  . . . V 0  may be used in establishing a desired mapping between digital image data values (e.g., 0 . . . 255 or other suitable range of values) and analog voltage levels for use as analog image data signals for the pixels of display  14 . To display images on display  14 , image buffer  118  may supply digital image data to gamma multiplexer  110  via path  116 . Gamma multiplexer  110  may supply a desired voltage from one of lines  112  to gamma multiplexer  114  to use as data signal D in response to the digital image data signal received from image buffer  118  on path  116 . The gamma block circuitry and gamma multiplexer circuitry of display  14  may be used to supply signals to multiple data lines. The display driver circuitry of display  14  may, for example, include gamma block circuitry and gamma multiplexer circuitry that implement the functions of gamma block  108  and gamma multiplexer  110  of  FIG. 5 . Each gamma multiplexer  110  may, for example, be associated with a respective one of the data lines in display  14  and may supply that data line with an appropriate data line signal. 
     Display  14  may contain subpixels of different colors. For example, display  14  may contain red pixels (subpixels), green pixels (subpixels), and blue pixels (subpixels). Data signals D may be demultiplexed onto corresponding subpixel data lines  136  using data line demultiplexer circuitry such as data line demultiplexer  134 . There may be a demultiplexer such as demultiplexer  134  associated with each column of red, green, and blue pixels. During operation, the voltage on line  114  may be placed in a state appropriate for a red subpixel while control signal MUXR is taken high to direct demultiplexer  134  to route the voltage on line  114  to red subpixel data line R. Control signals MUXG and MUXB may likewise be asserted to demultiplex the signal on line  114  onto data lines G and B. 
     The circuitry of  FIG. 5  may be used for each of the data lines in display  14  that do not receive flash region data (i.e., data lines that do not overlap the flash region). In the example of  FIG. 5 , these data lines include data lines D 0  . . . DN−1 and DM+1 . . . DF of display  14  of  FIG. 4 . Display driver circuitry of the type shown in  FIG. 6  may be used for the data lines in display  14  that are configured to receive either image data or flash data (i.e., lines DN . . . DM that overlap region  100  in the example of  FIG. 4 ). The display driver circuitry of  FIG. 6  includes a mode selection multiplexer circuitry for each data line (mode selection multiplexer  124 ). The mode of operation of the display driver circuitry of  FIG. 6  may be switched by control circuitry  16  between a normal image data loading mode and a flash data loading mode using mode selection signal MODE_SELECT. 
     Mode selection control signal MODE_SELECT may be deasserted whenever it is desired to route normal image data to subpixel data lines in the columns of display  14  associated with data lines DN . . . DM of  FIG. 4 . For example, MODE_SELECT may be deasserted when loading signals into the rows of pixels associated with gate lines G 0  . . . GK−1 and GL+1 . . . GF during image display operations (and during flash operations) and may also be deasserted when loading signals into the rows of pixels associated with gate lines GK . . . GL during image display operations. In this mode (sometimes referred to as a normal mode, image mode, or non-flash mode), image data from a gamma multiplexer (see, e.g., multiplexer  110  of  FIG. 5 ) that is supplied to multiplexer  124  at input  130  may be routed to line  132 . Demuliplexer  134  may demultiplex this signal onto subpixel data lines  136 . 
     Mode selection control signal MODE_SELECT may be asserted whenever it is desired to route flash data Df from line  128  to line  132  for loading into the pixels of flash region  100  (e.g., when loading signals into region  100  using data lines DN . . . DM and using gate lines GK . . . GL during flash mode operations in the example of  FIG. 4 ). 
     Flash data signals Df may be generated by flash digital-to-analog converter  122  based on a digital flash setting signal that control circuitry  16  supplies to converter  122  at control input  120 . Converter  122  may produce different values of Df for different flash brightness levels. For example, converter  122  may produce a relatively large voltage Vf for use as flash data Df when the flash setting on input  120  is set to a “high” setting, may produce a relatively low voltage Vf when the flash setting on input  120  is set to a “low” setting, and may produce an intermediate voltage Vf when the flash setting on input  120  is set to a “medium” setting. When high data values Df are loaded into the pixels of flash region  100 , the pixels of region  100  will produce bright output. The use of medium or low data values Df will result in corresponding medium or low output light levels from region  100 . The use of three different brightness settings is merely illustrative. Converter  122  may support more than three different brightness levels or fewer than three different levels. Converter  122  may also produce data values Df that are different for the subpixels of different colors in region  100 . This allows the color temperature or other color attributes of the output light produced by flash region  100  to be adjusted. Color adjustments may be made independently of brightness level adjustments or different colors may be associated with different brightness levels. Flash data Df is generally uniform across region  100  (i.e., all of pixels  22  in region  100  receive the same data: the same red subpixel value, the same green subpixel value, and the same blue subpixel value). If desired, data Df can be varied within region  100  to create flash illumination with a non-uniform intensity pattern. 
       FIG. 7  is a timing diagram showing how image data D may be loaded into the pixels of display  14 . Pixels  22  may be loaded with image data using circuitry of the type shown in  FIG. 5  and using circuitry of the type shown in  FIG. 6  while signal MODE_SELECT is deasserted. 
     As shown in  FIG. 7 , demultiplexer control signals MUXR, MUXG, and MUXB for demultiplexer  134  may be asserted in sequence while the circuitry of each gamma block  108  and each gamma multiplexer  110  is being used to produce desired values of data signal D on each data line  114 . As MUXR is asserted, the current value of D is routed to a column of red subpixels. Assertion of MUXG and MUXB likewise are used to route the current value of D for each data line to columns of green and blue pixels, respectively. MODE_SELECT may be deasserted during the loading of normal image data to ensure that the data signals that are supplied to input  130  of multiplexer  124  of  FIG. 6  are routed to data line  132 . 
       FIG. 8  is a timing diagram showing how flash data Df may be loaded into the pixels of region  100 . During flash data loading operations, MODE_SELECT may be asserted to ensure that the flash data signals that are supplied to input  128  of multiplexer  124  of  FIG. 6  from converter  122  are routed to data line  132 . As shown in  FIG. 8 , demultiplexer control signals MUXR, MUXG, and MUXB for demultiplexer  134  may be asserted in sequence while gamma converter  122  is being used to produce desired values of data signal Df on each data line  114  for each of the different colors of subpixels in region  100 . As MUXR is asserted, the current value of Df is routed to a column of red subpixels. Assertion of MUXG and MUXB may likewise be used to respectively route the current value of Df to columns of green and blue pixels in region  100 . Aside from changing the value of Df for each subpixel color, the value of Df is generally not changed so that all of region  100  is illuminated uniformly. Configurations in which region  100  is not illuminated uniformly may be handled by directing converter  122  to vary the value of Df for different portions of region  100 . 
       FIG. 9  is a flow chart of illustrative steps involved in loading image data and flash data into pixels  22  of display  14 . 
     During the operations of step  140 , the display driver circuitry of  FIG. 5  and  FIG. 6  may load image data into each of the rows of display  14  that do not overlap flash region  100 . As an example, gate lines G 0  . . . GK−1 may be asserted in sequence while image data is presented to all data lines D 0  . . . DF. 
     In situations in which no flash data is to be presented (e.g., in situations in which flash region  100  is being used to display an image and is not being used to produce flash illuminations), the operations of step  140  may be used to load data into all rows of display  14  (e.g., rows GK . . . GF) while image data is presented to all data lines D 0  . . . DF. Once an entire frame of image data has been loaded into display  14  and displayed for a user, processing may loop back to step  140 , as indicated by line  142 , so that another frame of image data may be processed. 
     In situations in which flash data is to be presented in flash region  100 , signal MODE_SELECT may be asserted (step  144 ). During step  144 , the gate lines of display  14  that overlap flash region  100  may be asserted in sequence. At the same time, image data may be presented to the data lines that do not overlap the flash region while flash data is simultaneously presented to the data lines that do overlap the flash region. The remainder of the pixels in display  14  (i.e., the pixels in rows below the flash region, if any) may then be loaded with image data by deasserting MODE_SELECT and processing initiated for a fresh frame (step  140 ). 
     If desired, the display driver circuitry for display  14  may be configured to allow the position of flash region  100  to be adjusted by control circuitry  16 . This approach may be used, for example, to allow a fingerprint(s) to be captured at a number of different locations on display  14 . 
     Consider, as an example, the illustrative display driver circuitry of  FIG. 10 . In the example of  FIG. 10 , the gamma multiplexers of display  14  are provided with a first input that receives the output of gamma block  108  and a second input that receives flash data Vf from the output of converter  122 . A flash control signal (e.g., FLASH_MODE) may be supplied to each gamma block  108 . When FLASH_MODE is deasserted for the gamma multiplexer  110 ′ for a given data line  114 , that data line is provided with image data signals D from the gamma block  108  at the first input of that gamma multiplexer  110 ′. This allows normal data to be loaded onto subpixel data lines  136 . When FLASH_MODE is asserted for the gamma multiplexer  100 ′ for a given data line  114 , that data line is provided with flash data signals Df from the flash digital-to-analog converter  122  at the second input of that gamma multiplexer  110 ′. 
     The flash mode selection input for the gamma multiplexer circuitry may be used to adjust the position of the flash region. The inputs for each of gamma multiplexers  100 ′ may all be independent or groups of two or more of these inputs may be connected together to conserve circuit resources. In situations in which the FLASH_MODE signal in each column is independently adjustable by control circuitry  16 , control circuitry  16  can select a pattern of asserted and deasserted FLASH_MODE signals to adjust the horizontal position of flash region  100  to any desired location within display  14 . In situations in which there are fewer independently adjustable FLASH_MODE signals, the available horizontal positions for region  100  will be correspondingly restricted, but fewer different control lines will be required. Vertical positioning of region  100  may be implemented by asserting FLASH_MODE in appropriate columns while a set of gate lines that overlap the desired position of region  100  are being asserted. 
     During manufacturing, display  14  may be calibrated. For example, test image data may be displayed on display  14  while image calibration measurements are made and test flash data may be displayed in a test flash region of display  14  while flash calibration measurements are made. Resulting calibration data for display  14  (e.g., global image calibration data, region-specific image calibration data, pixel-by-pixel image calibration data, and flash region calibration data for all pixels, blocks of pixels, or each pixel in flash region  100 ) can then be stored in display  14  and used in producing calibrated image data with gamma block  108  and in producing calibrated flash illumination. 
     Control circuitry  16  may monitor sensors and other input-output devices  12  to determine when to initiate flash mode operations. For example, circuitry  16  may monitor input from a capacitive touch sensor to determine when a user&#39;s finger has been placed over flash region  100 . The flash region can then be illuminated so that an array of light detectors  84  in this region can be used to capture a fingerprint (as an example). If desired, other types of sensor input can be processed by control circuitry  16  to determine when a user&#39;s finger or other object is in flash region  100  for fingerprint capture. For example, components  84  or other components in device  10  may include infrared emitters and sensors that form light-based proximity sensors. When a proximity sensor reading indicates that a user&#39;s finger is present, control circuitry  16  can illuminate region  100  and gather sensor readings from an array of light sensor components  84 . In some situations, components  84  (e.g., light sensors) may output signals with a given level during normal ambient lighting conditions and may exhibit output signals with a temporarily reduced level when normal ambient lighting conditions are still present but a finger or other object is shadowing components  84 . Force sensors (capacitive sensors, strain gauges, etc.) may be use to detect the presence of a users finger. In general, proximity sensor measurements, capacitive touch sensor measurements, ambient light sensor shadow detection, actuation of a force sensor (e.g., a strain gauge, etc.), actuation of a switch under region  100 , or other suitable arrangements may be used in determining when to activate flash region  100  and capture a fingerprint. The foregoing examples are merely illustrative. 
     In operations such as fingerprint capture operations, it may be desirable for the illumination provided by the pixels of flash region  100  to be uniform. Accordingly, each of the pixels in this region may be provided with the same flash data Df. The color of the light produced in region  100  can be adjusted by adjusting the relative magnitude of the output produced by the red, green, and blue subpixels (or subpixels of other suitable colors) within this uniform data for region  100 . If desired, different portions of region  100  can be provided with correspondingly different values of data Df (e.g., to produce patterned flash illumination, graded flash illumination, or flash region output with other non-uniform characteristics). Moreover, the non-flash region of display  14  may be used to display output with a particular brightness (normal, higher than normal, or lower than normal), a particular color (blue, green, red, or other colors), may be used to display a pattern of non-image data, may be used to display modified image data, or may be used to display other desired output during the use of flash region  100  to produce flash output. The use of the non-flash regions of display  14  to display normal image data while flash region  100  supplies uniform flash output is merely illustrative. 
     If desired, display  14  may be provided with a first region (e.g., region  100  of  FIG. 4  or any other suitable portion of display  14 ) that has a brightness that is independently adjustable from the brightness of a second region of display  14  (e.g., the rest of display  14  of  FIG. 4  outside of region  100 ). The brightness (maximum pixel luminance) in the first and second regions may be independently adjusted by using separate brightness control signals for the first and second regions. Using this type of arrangement, a local area of display  14  (e.g., region  100 ) may be provided with a boosted brightness for illumination purposes (e.g., to serve as a flash illumination for an array of light sensors, etc.) or may be provided with a locally dimmed or brightened appearance to enhance a user&#39;s interaction with content in the locally dimmed or brightened local area. 
       FIG. 11  is a diagram of illustrative display driver circuitry of the type that may be used to adjust display brightness in a local region of a display independently from the rest of the display. The display driver circuitry of  FIG. 11  may handle an expanded gamma. For example, instead of converting digital image data into 256 gray voltage levels, the display driver circuitry of  FIG. 11  may convert digital image data and brightness control data into 1024 voltage levels. 
     As shown in  FIG. 11 , image data mapping circuitry  150  may receive 8-bit image data and may produce corresponding 10-bit gamma block digital input data for gamma multiplexer circuitry  110  on path  116 ′. Circuitry  150  therefore maps 8-bit input image data to 10-bits of output data on path  116 ′ at the digital input to gamma multiplexer circuitry  110  to cover up to 1024 voltages levels. The maximum luminance associated with these 1024 values may exceed the maximum luminance available in a comparable  256  level system (as an example), so that display  14  can exhibit locally enhanced brightness. The ability of display  14  to exhibit enhanced display brightness can be provided to all of the pixels in display  14  (i.e., all of display  14  may have pixels  22  that are provided with up to 1024 voltage levels) or only portions of display  14  may have the ability of display  14  to exhibit enhanced display brightness (i.e., only pixels  22  in region  100  may receive up to 1024 voltage levels over corresponding data lines  114 ). 
     Mapping circuitry  150  may include 8-bit to 10-bit mapping circuits  156  and  158 . Circuit  158  may receive local brightness control signals on brightness control input  154  for a region such as region  100  and circuit  156  may receive brightness control signals on brightness control input  152  for the rest of display  14 . Image data for local region  100  of display  14  may be provided to mapping circuit  158  from image buffer  118  at input  116 A. Image data for the rest of display  14  may be provided to mapping circuit  156  from image buffer  118  at input  116 B. The image data at inputs  116 A and  116 B may be 8-bit data or may have any other suitable bit size. The corresponding output data on path  116 ′ may be 10-bit data or may have any other suitable size larger than the input data. 
     Mapping circuitry  150  may produce an output that is based on the image data and brightness control data presented to the inputs of mapping circuitry  150 . Mapping circuit  158  may, for example, produce an output that is equal to the product of the grey level (image data) presented at input  116 A and the brightness control signal for region  100  that is presented at input  154 , whereas mapping circuit  156  may produce an output that is equal to the product of the grey level (image data) presented at input  116 B and the brightness control signal for the region of display  14  other than region  100  that is presented at input  152 . 
     There may be two separate sets of gamma mappings for region  100  and the rest of display  14  (i.e., two corresponding sets of curves relating input digital data values to the analog voltage levels produced by circuitry  110  for pixels  22 ). Consider, as an example, the gamma curves of  FIG. 12 , which include a first set of curves (curves  160 ) and a second set of curves (curves  164 ). Each of the curves in each set of curves corresponds to a different brightness setting. In the example of  FIG. 12 , the maximum pixel luminance in region  100  corresponds to analog pixel voltage V[ 1023 ] and is larger than the maximum pixel luminance in the rest of display  14 , which corresponds to analog pixel voltage VM. This is merely illustrative. The maximum pixel luminance for region  100  and the rest of display  14  may be the same or region  100  may have a maximum pixel luminance that is lower than the rest of display  14 . 
     In the illustrative configuration of  FIG. 12 , curves  160 , which correspond to region  100 , show how the pixels in region  100  may have a maximum luminance that lies within range  162  (i.e. a value from V[ 0 ] to V[ 1023 ]), depending on the current brightness setting at input  154 . Curves  162 , which correspond to the rest of display  14 , show how the pixels in the rest of display  14  may have a maximum luminance that lies within range  166  (i.e., a value from V[ 0 ] to VM), depending on the current brightness setting at input  152 . 
     The brightness of the content in region  100  can be adjusted using brightness setting  154  independently of the brightness of the content in the rest of display  14 , which is adjusted using brightness setting  152 . Region  100  can have a momentarily enhanced brightness (e.g., to produce a flash of illumination in configurations in which region  100  contains an array of light sensors  84 ) or can be provided with enhanced brightness for longer periods of time. While the brightness setting for region  100  is being momentarily enhanced, the digital image data corresponding to region  100  can be provided with a single value (e.g., to produce a block of solid white illumination) or may correspond to a pattern or part of an image. If desired, the independence of the brightness adjustments for region  100  and the rest of display  14  may be used to reduce the brightness of the pixels in region  100  relative to the pixels in the rest of display  14 . The use of separate brightness adjustments for region  100  and the rest of display  14  to produce a momentarily enlarged brightness in region  100  is merely illustrative. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20210329
Publication Date: 20220531
Grant Date: 20220531
Priority Date: 20151215
Inventors: AFLATOONI, KOOROSH
CHOI, MINHYUK
JANGDA, MOHAMMAD ALI
YOUN, SANG Y.
BI, YAFEI
GUILLOU, JEAN-PIERRE
YAO, WEI H.
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/148", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06V40/1318", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/148", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06V40/1318", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G5/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06V40/13", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2360/148", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06V40/1318", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06V40/13", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 64604805