PATENT DOCUMENT

Publication Number: US-10417964-B1
Application Number: US-201815947687-A
Country: US
Kind Code: B1

Title: Display with redundancy

Abstract:
A display with an array of pixels may be provided with redundant pixel control circuits. Switching circuitry may be used to couple pixel control circuits to light-emitting diodes for the pixels. The switching circuitry can be configured using control signals from non-volatile memory in decoder circuitry such as thermometer code decoder circuitry. During manufacturing, the display may be inspected for defects. Defective pixel control circuits can be replaced with redundant pixel control circuits so that the display operates satisfactory. The decoder circuitry may supply control signals to the switching circuitry to switch redundant pixel control circuitry into use while bypassing defective pixel control circuits.

Claims:
What is claimed is: 
     
       1. A display, comprising:
 a substrate; 
 an array of light-emitting diodes on the substrate; 
 display driver circuitry configured to supply image data to the array of light-emitting diodes on data lines and configured to supply control signals to the array of light-emitting diodes over control lines; 
 switching circuitry; 
 pixel control circuits coupled to the light-emitting diodes and the data lines by the switching circuitry, wherein the pixel control circuits include redundant pixel control circuits; and 
 a decoder circuit having non-volatile memory operable to receive configuration data and provide corresponding control signals to the switching circuitry to configure the switching circuitry to bypass a defective pixel control circuit in the pixel control circuits and switch the redundant pixel control circuits into use. 
 
     
     
       2. The display defined in  claim 1  wherein the decoder circuit comprises a thermometer code decoder circuit and wherein the switching circuitry includes first switches and second switches, wherein each light-emitting diode is coupled to a first respective pixel control circuit in the pixel control circuits by a respective one of the first switches and is coupled to a second respective pixel control circuit in the pixel control circuits by a respective one of the second switches. 
     
     
       3. The display defined in  claim 2  wherein the display driver circuitry includes driver circuits, third switches, and fourth switches and wherein each driver circuit has an output that is coupled to a first respective data line in the data lines by a respective one of the third switches and is coupled to a second respective data line in the data lines by a respective one of the fourth switches. 
     
     
       4. The display defined in  claim 3  wherein the driver circuits comprise column drivers, wherein the data lines are associated with columns of the pixel control circuits, wherein the redundant pixel control circuits are a column of redundant pixel control circuits, and wherein the thermometer code decoder circuit comprises a thermometer code column decoder. 
     
     
       5. The display defined in  claim 4  further comprising inverters, first control lines, and second control lines, wherein the thermometer code decoder circuit has outputs each of which is coupled to a respective one of the second control lines and each of which is coupled by a respective one of the inverters to a respective one of the first control lines. 
     
     
       6. The display defined in  claim 5  wherein the first control lines are coupled to the first switches. 
     
     
       7. The display defined in  claim 6  wherein the second control lines are coupled to the second switches. 
     
     
       8. The display defined in  claim 7  wherein the first control lines are coupled to the third switches. 
     
     
       9. The display defined in  claim 8  wherein the second control lines are coupled to the fourth switches. 
     
     
       10. The display defined in  claim 1  wherein the light-emitting diodes comprise organic light-emitting diodes. 
     
     
       11. The display defined in  claim 1  wherein the light-emitting diodes are each formed in a respective crystalline semiconductor die. 
     
     
       12. The display defined in  claim 1  wherein the substrate is a crystalline silicon substrate. 
     
     
       13. The display defined in  claim 12  wherein the pixel control circuits are formed in the substrate. 
     
     
       14. The display defined in  claim 1  wherein pixel control circuits include rows and columns of pixel control circuits, wherein each column of pixel control circuits is associated with a respective one of the data lines and wherein the redundant pixel control circuits are formed from one of the rows of pixel control circuits. 
     
     
       15. A display, comprising:
 an array of light-emitting diodes configured to display images; 
 an array of pixel control circuits including a column of redundant pixel control circuits; 
 display driver circuitry configured to supply image data to columns of the pixel control circuits on data lines and configured to supply control signals to rows of the pixel control circuits on horizontal control lines; 
 switching circuitry configured to selectively couple each of the light-emitting diodes to two respective columns of the pixel control circuits; and 
 decoder circuitry configured to control the switching circuitry to switch the redundant column of pixel control circuits into use and bypass a column of the pixel control circuits that contains a defect. 
 
     
     
       16. The display defined in  claim 15  wherein the column of redundant pixel control circuits is one of multiple columns of redundant pixel control circuits in the array of pixel control circuits and wherein the array of pixel control circuits includes multiple blocks of pixel control circuits each including a respective one of the multiple columns of redundant pixel control circuits. 
     
     
       17. The display defined in  claim 15  wherein the decoder circuitry comprises thermometer code decoder circuitry having nonvolatile memory configured to store thermometer code data. 
     
     
       18. The display defined in  claim 15  further comprising a crystalline silicon substrate on which the array of light-emitting diodes is formed, wherein at least some of the display driver circuitry is formed in the crystalline silicon substrate. 
     
     
       19. A display, comprising:
 an array of light-emitting diodes configured to display images; 
 an array of pixel control circuits including a row of redundant pixel control circuits; 
 display driver circuitry configured to supply image data to columns of the pixel control circuits on data lines and configured to supply control signals to rows of the pixel control circuits on horizontal control lines; 
 switching circuitry configured to selectively couple each of the light-emitting diodes to two respective rows of the pixel control circuits; and 
 decoder circuitry configured to control the switching circuitry to switch the redundant row of pixel control circuits into use and bypass a row of the pixel control circuits containing a defect. 
 
     
     
       20. The display defined in  claim 19  wherein the switching circuitry includes rows of switching circuits, each switching circuit coupled between a pixel control circuit in a first respective row of the pixel control circuits and a pixel control circuit in a second respective row of the pixel control circuits and wherein the decoder circuitry includes non-volatile memory.

Description:
This application claims the benefit of provisional patent application No. 62/519,676, filed on Jun. 14, 2017, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with displays. 
     Electronic devices often include displays. Displays include arrays of individually adjustable pixels for producing images. Displays may include hundreds or thousands of rows and columns of pixels. Due to the relatively large number of pixels in a display, it is possible for a pixel circuit in a display to contain a manufacturing fault. This can lead to undesirable visual artifacts in a display. 
     SUMMARY 
     An electronic device may be provided with a display. The display may have an array of pixels for displaying images. The pixel array may be provided with redundant pixel control circuits that can be switched into use to overcome manufacturing defects. 
     Switching circuitry may be used to couple pixel control circuits including the redundant pixel control circuits to light-emitting diodes for the pixels. The switching circuitry can be configured using control signals from non-volatile memory in decoder circuitry such as a thermometer code decoder circuit. 
     During manufacturing, the display may be inspected for defects. Defective pixel control circuits can be replaced with redundant pixel control circuits so that the display operates satisfactory. When a defect is detected, corrective thermometer code configuration data may be loaded into the non-volatile memory of the decoder circuitry. During operation, the decoder circuitry may supply control signals to the switching circuitry based on the loaded configuration data. The control signals configure the switching circuitry to switch redundant pixel control circuitry into use while bypassing defective pixel control circuits. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an illustrative electronic device having a display in accordance with an embodiment. 
         FIG. 2  is a diagram of an illustrative display in accordance with an embodiment. 
         FIG. 3  is a diagram of an illustrative pixel circuit for a light-emitting diode display in accordance with an embodiment. 
         FIG. 4  is a diagram of an illustrative display with redundant circuitry in accordance with an embodiment. 
         FIG. 5  is flow chart of illustrative operations involved in testing and configuring a display with redundant circuitry in accordance with an embodiment. 
         FIG. 6  is a diagram of an illustrative display containing multiple columns of redundant pixel control circuitry in accordance with an embodiment. 
         FIG. 7  is a diagram of an illustrative display with a row of redundant pixel control circuitry in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with a display having redundant circuitry is shown in  FIG. 1 . Electronic device  10  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, a head-mounted device such as virtual reality or mixed reality equipment (e.g., glasses, googles, a helmet, etc.), or other wearable or miniature device, a display, a computer display that contains an embedded computer, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, or other electronic equipment. 
     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, light-emitting diodes and other status indicators, data ports, etc. 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. A touch sensor for display  14  may be formed from electrodes formed on a common display substrate with the pixels of display  14  or may be formed from a separate touch sensor panel that overlaps the pixels of display  14 . If desired, display  14  may be insensitive to touch (i.e., the touch sensor may be omitted). 
     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 . 
     Display  14  may be any suitable type of display (e.g., a liquid crystal display, an electrophoretic display, a microelectromechanical systems display, an organic light-emitting diode display, a display having an array of light-emitting diodes formed from respective crystalline semiconductor dies, etc.). With one illustrative configuration, which may sometimes be described herein as an example, display  14  may be a light-emitting diode display having an array of light-emitting diode pixels (e.g., organic light-emitting diode pixels each having an organic light-emitting diode, pixels formed from light-emitting diodes on respective crystalline semiconductor dies, etc.). 
     A schematic diagram of an illustrative display is shown in  FIG. 2 . As shown in  FIG. 2 , display  14  may include layers such as substrate layer  28 . Substrate  28  and, if desired, other layers in display  14 , may be formed from layers of material such as glass layers, polymer layers (e.g., flexible sheets of polyimide or other flexible polymers), etc. Substrate  28  may be planar and/or may have one or more curved portions. Substrate  28  may have a rectangular shape with left and right vertical edges and upper and lower horizontal edges or may have a non-rectangular shape. If desired, substrate  28  may be formed from a semiconductor. For example, substrate  28  may be a silicon substrate (e.g., a crystalline silicon layer such as a crystalline silicon die). In this type of configuration, display driver circuitry, pixel control circuits, switching circuitry, and other control circuitry for display  14  may be formed from transistors and other circuitry in substrate  28 . 
     Display  14  may have an array of pixels  24 . Each pixel  24  may have a light-emitting diode such as an organic light-emitting diode or a light-emitting diode formed from a crystalline semiconductor die (sometimes referred to as a micro-light-emitting diode). Pixels  24  of pixel array  26  may be organized in rows of pixels  24  (e.g., rows RW1, RW2, RW3 . . . ) and columns of pixels  24  (e.g., columns CL1, CL2, and CL3 . . . ). There may be any suitable number of rows and columns in the array of pixels  24  (e.g., ten or more, one hundred or more, or one thousand or more). Display  14  may include pixels  24  of different colors. As an example, display  14  may include red pixels that emit red light, green pixels that emit green light, and blue pixels that emit blue light. Configurations for display  14  that include pixels of other colors may be used, if desired. Pixel array  26  forms an active area of display  14  that displays images for a user. Inactive regions may border pixel array  26 . Circuitry such as display driver circuitry  18  may be located in the inactive regions. 
     Display driver circuitry  18  may include thin-film transistor circuitry (e.g., thin-film transistor circuits formed on substrate  28 ) and/or may include one or more integrated circuits mounted to substrate  28  and/or coupled to substrate  28  through one or more additional substrates. Signal paths such as signal path  30  may couple display driver circuitry  18  to control circuitry  16 . 
     During operation, the control circuitry of device  10  (e.g., control circuitry  16  of  FIG. 1 ) may supply circuitry such as display driver circuitry  18  with information on images to be displayed on display  14 . To display the images on display pixels  24 , display driver circuitry  20  may supply corresponding image data to data lines D while issuing clock signals and other control signals to supporting display driver circuitry such as gate driver circuitry  22 . Gate driver circuitry  22  may produce gate line signals (sometimes referred to as scan signals, emission enable signals, etc.) or other control signals for pixels  22 . The gate line signals may be conveyed to pixels  24  using control signal lines such as gate lines G. There may be one or more gate lines per row of pixels  24 . Display driver circuitry such as gate driver circuitry  22  may be located along the edges of display  14  (e.g., along the left and/or right edges of display  14  as shown in  FIG. 2 ) or elsewhere in display  14 . Display driver circuitry such as display driver circuitry  20  may be located above and/or below pixel array  26  or elsewhere in display  14 . The configuration of  FIG. 2  is merely illustrative. 
     Display driver circuitry  20  may supply data signals onto a plurality of corresponding data lines D while display driver circuitry such as gate line driver circuitry  22  issues control signals on gate lines G. With the illustrative arrangement of  FIG. 2 , data lines D run vertically through display  14  and are associated with respective columns of pixels  24 , whereas gate lines G (sometimes referred to as scan lines, emission lines, horizontal control lines, etc.) run horizontally through display  14 . There may be one gate line G or multiple gate lines G associated with each row of pixels  24 . 
     During operation, gate driver circuitry  22  may assert gate line signals on the gate lines G in display  14  in a predetermined pattern. For example, gate driver circuitry  22  may receive clock signals and other control signals from display driver circuitry  20  and may, in response to the received signals, use gate lines G to load rows of pixels  24  in sequence from data lines D. In this way, control circuitry in device  10  such as display driver circuitry  18  may provide pixels  24  with signals that direct light-emitting diodes in pixels  24  to generate light for displaying a desired image on display  14 . 
       FIG. 3  is a diagram of an illustrative pixel circuit for pixel  24 . As shown in  FIG. 3 , pixel  24  may include light-emitting diode  32  and associated pixel control circuit  34 . In the illustrative configuration of  FIG. 3 , the cathode of diode  32  is coupled to node  56  (e.g., ground) and the anode of diode  32  is coupled to pixel control circuit  34 . Other configurations for coupling diode  32  to pixel control circuit  34  may be used, if desired. 
     Pixel control circuit  34  may include transistors for receiving and storing data signals from data line D in response to control signals on one or more horizontal control paths such as gate line(s) G. Pixel control circuit  34  may also include circuitry for applying a current proportional to the stored data bit on pixel  24  to light-emitting diode  32 , so that light-emitting diode  32  emits a desired amount of light  36 . 
     When manufacturing displays that have numerous rows and columns of pixels, there is a potential that a pixel circuit may be manufactured with a defect. A pixel circuit defect might, for example, cause a pixel to be stuck off (no current passing through diode  32 ) or stuck on (current passing through diode  32 ). Pixels that are stuck on emit light even in situations in which a black image is being displayed on display  14 , causing these pixels to appear as bright visual defects on display  14 . 
     To avoid undesirable visual artifacts on display  14 , display  14  may contain redundant pixel control circuitry such as one or more lines of pixel control circuits  34  (e.g., one or more rows and/or columns of redundant pixel control circuits  34 ). If defective pixel control circuitry is detected during manufacturing, the redundant pixel control circuitry may be switched into use in place of the defective pixel control circuitry. 
     Consider, as an example, display  14  of  FIG. 4 . As shown in  FIG. 4 , display  14  may include pixel array  26 . Pixel array  26  (in the simplified example of  FIG. 4 ) has three rows and six columns of light-emitting diodes  32 . Pixel array  26  also has three rows and seven columns of pixel control circuits  34 . The first six columns of pixel control circuits  34  (e.g., the leftmost six columns of  FIG. 4 ), which may sometimes be referred to as regular pixel control circuits or normal pixel control circuits, may be used when pixel array  26  is defect free. In this situation, the seventh (rightmost) column of pixel control circuits  34  (column  58 ), which may sometimes be referred to as a column of redundant pixel control circuits, is not needed. When a column of the pixel control circuits in pixel array  26  contains a defect, however, the column of redundant pixel control circuits can be switched into use in place of the defective column. In this way, sufficient pixel control circuits may be made available for controlling light-emitting diodes  32  even in the presence of a pixel control circuit manufacturing defect. 
     Display  14  may include switching circuitry that can be configured during manufacturing (e.g., using configuration data in non-volatile memory in display  14 ). The switching circuitry can be configured to switch the normal pixel control circuitry or the redundant pixel control circuitry into use, as appropriate. 
     As shown in  FIG. 4 , display  14  may include display driver circuitry  20 . Display driver circuitry  20  may include six column drivers  38  and switching circuitry such as switches  40  and  42 . Each column of pixel control circuits  34  may have an associated data line D. In the present example, there are six regular (normal) data lines D and one redundant data line D associated with column  58  of redundant pixel control circuits  34 . The output of each of the six column drivers  38  is coupled to a respective one of the regular data lines via a respective one of switches  40  and is coupled to a data line in a successive column via a respective one of switches  42 . In this way, the last column driver  38  has an opportunity to be selectively coupled to the data line D in the redundant column (column  58 ) of pixel control circuits  34  when needed to accommodate a detected defect in a pixel control circuit  34  in array  26 . 
     Each switch  40  may be turned on and off by control signals from a respective one of inverters  46  over a respective switch control line  44 . Inverters  46  may be coupled to the outputs of column decoder  50  and may sometimes be referred to as inverter circuitry or column decoder circuitry. The output of the column driver  38  in each column is coupled to the data line in a successive column by a respective one of switches  42 . Each switch  42  may be turned on and off by control signals received over a respective switch control line  48 . 
     Thermometer column decoder  50  (e.g., circuitry in display driver circuitry  18 ) may have non-volatile memory cells (e.g., a row of cells that receive thermometer code configuration data). Each non-volatile memory cell may be loaded with a binary data bit during manufacturing. Once loaded, column decoder  50  may supply associated control signals on its outputs. For example, in the arrangement of  FIG. 4  in which there are six normal columns of pixel control circuits  34 , column decoder  50  may have six non-volatile memory cells that supply six corresponding control signals (x[5] . . . x[0]) to six corresponding switch control lines  48 . 
     Inverters  46  are used to invert the control bits on the outputs of column decoder  50 , so that the control signals on lines  44  are complementary to the control signals on lines  48 . As a result, when a given decoder output is a logic one (e.g., a high voltage level), the line  48  coupled to that output will carry a logic one and the line  44  coupled to the output of the associated inverter  46  will be a logic zero. 
     The switches  40  and  42  in each column form a column driver output switching circuit. Switches  42  are coupled to lines  48  and switches  40  are coupled to lines  44 , so the states of switches  40  and  42  in the column driver output switching circuit of each column will be complementary to each other (e.g., in each column a respective switch  40  will be on while a respective switch  42  will be off or vice versa). In its first state (sometime referred to as a regular or normal state), this switching circuit routes data from the output of the column driver  38  in a given column into the pixel control circuits  34  in that column. In its second state (sometimes referred to as a bypass state), this switching circuit routes data from the output of the column driver  38  in a given column into the pixel control circuits  34  in a subsequent column (e.g., the adjacent column to the right in the example of  FIG. 4 ). Multiple columns may be shifted in this way when needed to accommodate a defect. The switching circuitry formed by switches  40  and  42  therefore allows a column of pixel control circuits that contains a defect to be bypassed and allows redundant pixel control circuits to be switched into use in place of the bypassed defective pixel control circuits. 
     Each light-emitting diode  32  is coupled to a pixel control circuit  34  in the same column as that light-emitting diode by a respective switch  52  and is coupled to a pixel control circuit  34  in the subsequent column by a respective switch  54 . When a column is free of defects, switches  52  in that column can be turned on and switches  54  in that column can be turned off by asserting the control signal on line  44  of that column (e.g., by taking line  44  high) and deasserting the control signal on line  48  of that column (e.g., by taking line  48  low). Pairs of switches  52  and  54  therefore form switching circuits that can be placed in a regular or bypass mode as needed to selectively bypass a column of pixel control circuits  34  that contains a defect. 
     In the example of  FIG. 4 , pixel control circuit  34 D is defective. Accordingly, thermometer code configuration data (e.g., x[5]=0, x[4]=0, x[3]=0, x[2]=0, x[1]=1, and x[0]=1) can be loaded into the non-volatile memory of column decoder  50  during manufacturing. The thermometer code data contains all zeros for the initial (leftmost) defect-free columns and contains ones for the defective column and all subsequent columns (the columns where data is shifted). This causes decoder  50  to provide control signals on lines  44  and  46  that configure the switching circuitry of display  14  to bypass defective pixel control circuit  34 D. In particular, the outputs of the leftmost four column drivers  38  are routed respectively to the leftmost four columns of pixel control circuits  34 . The fifth column of pixel control circuits  34  (i.e., the column containing defective pixel control circuit  34 D) is bypassed. The outputs of the rightmost two column drivers  38  are shifted to the rightmost two columns of pixel control circuits  34  (e.g., the last of the six columns of regular pixel control circuits  34  and the column of redundant pixel control circuits  34 , respectively). 
       FIG. 5  is a flow chart of illustrative operations associated with configuring a display with redundant pixel control circuitry to accommodate defects. During the operations of  FIG. 5 , a tester may use a camera or other optical inspection equipment to monitor the output of display  14  and thereby determine if any pixels are defective (e.g., by detecting stuck on or stuck off pixels, etc.). The tester may supply test images to display driver circuitry  18  while the camera is monitoring the output of light-emitting diodes  32 . 
     Initially (block  60 ), the tester or other equipment (e.g., non-volatile memory programing equipment) may load default configuration data into display driver circuitry  18  (e.g., decoder  50 ) that places the switching circuitry into its regular operating state. In its regular (default) column configuration, pixel control circuits  34  of redundant column  58  are switched out of use. 
     During the operations of block  62 , display  14  may be turned on and loaded with a test image while pixel control circuits  34  are configured to operate in their default configuration. 
     During the operations of block  64 , the camera or other monitoring device in the tester may be used to check pixel array  26  to determine whether any of light-emitting diodes  32  are emitting abnormal amounts of light. In response to detecting a column of pixel control circuits  34  that contain a defect (block  66 ), the tester can determine the location of the defective column (block  68 ) and can create an updated set of configuration data during the operations of block  70 . For example, thermometer code configuration data or configuration data that is encoded using other encoding techniques may be generated and supplied to column decoder  50  to configure the redundancy switching circuitry of display  14  so that the defective column is bypassed, as described in connection with bypassing defect  34 D of  FIG. 4 . 
     Once the defect has been bypassed, the optical checking operations of block  64  will indicate that display  14  is operating satisfactorily (e.g., no defects will be present at block  72 ). The configuration data associated with this satisfactory configuration for display  14  may then be retained in the non-volatile memory (NVM) of decoder  50  (block  74 ). Even if power is turned off to display  14 , decoder  50  will retain the configuration data. This ensures that the switching circuitry of display  14  is configured so that defective circuitry is bypassed and display  14  operates satisfactorily during operation of device  10  by a user. 
     If desired, display  14  may be provided with multiple columns of redundant pixel control circuits  34 . Display  14  may, as an example, be partitioned into multiple blocks such as blocks B 1 , B 2 , and B 3  in the example of  FIG. 6 . Each block may have a respective column of redundant pixel control circuits  34 , as indicated by redundant columns  58 . Within each block, display  14  may have switching circuitry and column decoder circuitry such as switches  40 ,  42 ,  52 , and  54  and circuits  46  and  50  of  FIG. 4  to allow a column in that block that contains a defective pixel control circuit  34  to be bypassed. This type of arrangement allows a display with more than one defect to be repaired. For example, display  14  can be configured to operate satisfactorily even if a first defect is identified in block B 1 , a second defect is identified in block B 2 , and a third defect is identified in block B 3 . There may be any suitable number of blocks (partitions) and any suitable number of redundant pixel control circuits in display  14  (e.g., at least 5, at least 10, at least 50, fewer than 100, fewer than 20, fewer than 4, or other suitable number). 
       FIG. 7  shows how redundancy may be implemented using a row-wise shifting scheme. As shown in the example of  FIG. 7 , a redundant row  58 R of pixel control circuits  34  may be provided in display  14 . Thermometer row decoder  50 R may be used in suppling control signals to switching circuits  76  (each of which may contain a first switch coupled to a pixel control circuit  34  in a given row and each of which may contain a second switch coupled to a pixel control circuit  34  in a subsequent row). In the absence of defects, switching circuitry such as switching circuits  76  can be configured to switch pixel control circuit  34  in non-redundant rows into use. These pixel control circuits  34  may then supplying control signals (drive currents based on loaded data) to respective light-emitting diodes  32  during operation of display  14 . When a row containing a defective pixel control circuit  34  is identified during testing, switching circuitry such as switching circuits  76  can be configured so that the row of pixel control circuits containing the defective pixel circuit can be bypassed and redundant pixel control circuits  34  in redundant row  58 R switched into use. 
     As these examples demonstrate, display  14  may be provided with redundancy circuitry that allows redundant pixel control circuitry to be switched into use to replace defective pixel control circuitry. The redundant pixel control circuitry may include one or more lines of redundant pixel control circuits. For example, horizontal strips (rows) of pixel control circuits can be provided in configurations of the type shown in  FIG. 7  and/or vertical strips (columns) of pixel control circuits can be provide in configurations of the type shown in  FIG. 5 . Switching circuitry may be configured using control signals from decoder circuitry containing configuration data stored in non-volatile memory. The switching circuitry may include switches such as transistor-based switches. For example, each switch may be implemented using a respective n-channel metal-oxide-semiconductor transistor or other suitable transistor circuitry may be used in forming the switching circuitry for display  14 . 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20180406
Publication Date: 20190917
Grant Date: 20190917
Priority Date: 20170614
Inventors: LO, CHEUK CHI
TANG, Chun-ming
HUANG, CHUN-YAO
KNEZ, IVAN
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G2330/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3233", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2330/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/006", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2330/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3233", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2330/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2251/568", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L27/14609", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2330/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L27/3223", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/3244", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3233", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L27/124", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2330/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10D86/441", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10D86/60", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F39/803", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/88", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K71/861", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K71/861", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/12", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 67909137