Patent Application
20210012712
This relates generally to electronic devices with displays and, more particularly, to display driver circuitry for displays such as organic-light-emitting diode displays.
Electronic devices often include displays. For example, cellular telephones and portable computers include displays for presenting information to users.
Displays such as organic light-emitting diode displays have an array of display pixels based on light-emitting diodes. In this type of display, each display pixel includes a light-emitting diode and thin-film transistors for controlling application of a signal to the light-emitting diode to produce light.
An organic light-emitting diode display pixel includes a drive thin-film transistor connected to a data line via an access thin-film transistor. The access transistor may have a gate terminal that receives a scan signal via a corresponding scan line Image data on the data line can be loaded into the display pixel by asserting the scan signal to turn on the access transistor. The display pixel includes a current source transistor that provides current to the organic light-emitting diode to produce light.
Transistors in an organic light-emitting diode display pixel may be subject to process, voltage, and temperature (PVT) variations. Due to such variations, transistor threshold voltages between different display pixels may vary. Variations in transistor threshold voltages can cause the display pixels to produce amounts of light that do not match a desired image. Compensation schemes are sometimes used to compensate for variations in threshold voltage. Such compensation schemes typically involve sampling operations that are performed within each pixel during normal display operations and thus increase the time required to display images.
It is within this context that the embodiments herein arise.
An electronic device may include a display having an array of display pixels. The display pixels may be organic light-emitting diode display pixels. Each display pixel may have an organic light-emitting diode that emits light. A drive transistor (i.e., a current source transistor) in each display pixel may apply current to the organic light-emitting diode in that display pixel. The drive transistor may be characterized by a threshold voltage that is subject to random variations. Compensation circuitry may be used to measure sensing current from the drive transistor, to compare the sensing current to a predetermined current level, and to apply external compensation to the display pixel based on the comparison.
The display pixel may include a drive transistor, a gate setting transistor configured to drive the gate terminal of the drive transistor to a known reference voltage level, a data loading transistor for loading emission data into the display pixel and for outputting sensing current to the compensation circuitry, an organic light-emitting diode coupled in series with the drive transistor, an emission control transistor interposed between the drive transistor and the diode, and an anode reset transistor for resetting the anode terminal of the diode. The emission control transistor may be turned off during current sensing operations so that residue current and lateral leakage current at the organic light-emitting diode are prevented from contributing to the sensing current, thereby increasing the integrity of the external compensation operations (e.g., the emission control transistor is configured to electrically isolate and decouple any parasitic effects of the diode from the current sensing path).
In one suitable arrangement, a first portion of the transistors in the display pixel are semi-conducting oxide transistor to reduce leakage, whereas a second portion of the transistors in the display pixel are silicon transistors to increase performance. In another suitable arrangement, all of the transistors in the display pixel are semiconducting-oxide transistors to minimize power consumption. In one implementation, the emission control transistor and the anode reset transistor may be controlled using the same emission control signal. In another implementation, the anode reset transistor is controlled by a separate scan control signal that is different than the emission control signal.
An illustrative electronic device of the type that may be provided with an organic light-emitting diode (OLED) display is shown in
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, click wheels, 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.
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 in input-output devices.
Display driver circuitry such as display driver integrated circuit 15 may be coupled to conductive paths such as metal traces on substrate 24 using solder or conductive adhesive. If desired, display driver integrated circuit 15 may be coupled to substrate 24 over a path such as a flexible printed circuit or other cable. Display driver integrated circuit 15 (sometimes referred to as a timing controller chip) may contain communications circuitry for communicating with system control circuitry 16 over path 125. Path 125 may be formed from traces on a flexible printed circuit or other cable. Control circuitry 16 (see
During operation, the control circuitry may supply display driver integrated circuit 15 with information on images to be displayed on display 14. To display the images on display pixels 22, display driver integrated circuit 15 may supply clock signals and other control signals to display driver circuitry such as row driver circuitry 18 and column driver circuitry 20. For example, data circuitry 17 may receive image data and process the image data to provide pixel data signals to display 14. The pixel data signals may be demultiplexed by column driver circuitry 20 and pixel data signals D may be routed to each pixel 22 over data lines 26 (e.g., to each red, green, or blue pixel). Row driver circuitry 18 and/or column driver circuitry 20 may be formed from one or more integrated circuits and/or one or more thin-film transistor circuits.
Display driver integrated circuit 15 may include compensation circuitry 17 that helps to compensate for variations among display pixels 22 such as threshold voltage variations. Compensation circuitry 17 may, if desired, also help compensate for transistor aging. Compensation circuitry 17 may be coupled to pixels 22 via path 19, switching circuitry 21, and paths 23. Compensation circuitry 17 may include sense circuitry 25 and bias circuitry 27. Sense circuitry 25 may be used in sensing (e.g., sampling) voltages from pixels 22. During sense operations, switching circuitry 21 may be configured to electrically couple sense circuitry 25 to one or more selected pixels 22. For example, compensation circuitry 17 may produce control signal CTL to configure switching circuitry 21. Sense circuitry 25 may sample voltages such as threshold voltages or other desired signals from the pixels over path 19, switching circuitry 21, and paths 23. Bias circuitry 27 may include one or more driver circuits for driving reference or bias voltages onto nodes of pixels 22. For example, switching circuitry 21 may be configured to electrically couple path 19 to one or more selected pixels 22. In this scenario, bias circuitry 27 may provide reference signals to the selected pixels. The reference signals may bias nodes at the selected pixels at desired voltages for the sensing operations performed by sense circuitry 25.
Compensation circuitry 17 may perform compensation operations on pixels 22 using bias circuitry 27 and sense circuitry 25 to generate compensation data that is stored in storage 29. Storage 29 may, for example, be static random-access memory (SRAM). In the example of
Data circuitry 13 may include gamma circuitry 44 that provides a mapping of digital image data to analog data signals at appropriate voltage levels for driving pixels 22. Multiplexer 46 receives a set of possible analog data signals from gamma circuitry 44 and is controlled by the digital image data to select an appropriate analog data signal for the digital image data. Compensation data retrieved from storage 29 may be added to (or subtracted from) the digital image data by adder circuit 48 to help compensate for transistor variations (e.g., threshold voltage variations, transistor aging variations, or other types of variations) between different display pixels 22. This example in which compensation data is added as an offset to digital input image data is merely illustrative. In general, data circuitry 13 may process compensation data along with image data to produce compensated analog data signals for driving pixels 22.
In contrast to techniques that focus on performing in-pixel threshold canceling (such as by performing a reset phase followed by a threshold compensation phase), performing sensing and compensation in this way using compensation circuitry 17 outside of each pixel 22 allows for higher refresh rates (e.g., greater than 60 Hz refresh rate, at least 120 Hz refresh rate, etc.) and is sometimes referred to as “external” compensation. External variation compensation may be performed in the factory, in real time (e.g., during blanking intervals between successive image frames), or when the display is idle (as examples).
Row driver circuitry 18 may be located on the left and right edges of display 14, on only a single edge of display 14, or elsewhere in display 14. During operation, row driver circuitry 18 may provide row control signals on horizontal lines 28 (sometimes referred to as row lines, “scan” lines, and/or “emission” lines). Row driver circuitry may include scan line driver circuitry for driving the scan lines and emission driver circuitry for driving the emission lines.
Demultiplexing circuitry 20 may be used to provide data signals D from display driver integrated circuit (DIC) 15 onto a plurality of corresponding vertical lines 26. Demultiplexing circuitry 20 may sometimes be referred to as column driver circuitry, data line driver circuitry, or source driver circuitry. Vertical lines 26 are sometimes referred to as data lines. During display operations, display data may be loaded into display pixels 22 using lines 26.
Each data line 26 is associated with a respective column of display pixels 22. Sets of horizontal signal lines 28 run horizontally through display 14. Each set of horizontal signal lines 28 is associated with a respective row of display pixels 22. The number of horizontal signal lines in each row is determined by the number of transistors in the display pixels 22 that are being controlled independently by the horizontal signal lines. Display pixels of different configurations may be operated by different numbers of scan lines.
Row driver circuitry 18 may assert control signals such as scan and emission signals on the row lines 28 in display 14. For example, driver circuitry 18 may receive clock signals and other control signals from display driver integrated circuit 15 and may, in response to the received signals, assert scan control signals and an emission control signal in each row of display pixels 22. Rows of display pixels 22 may be processed in sequence, with processing for each frame of image data starting at the top of the array of display pixels and ending at the bottom of the array (as an example). While the scan lines in a row are being asserted, control signals and data signals that are provided to column driver circuitry 20 by DIC 15 may direct column driver circuitry 20 to demultiplex and drive associated data signals D (e.g., compensated data signals provided by data circuitry 13) onto data lines 26 so that the display pixels in the row will be programmed with the display data appearing on the data lines D. The display pixels can then display the loaded display data.
The sensing operation performed by sense circuitry 25 may involve sensing current from selected display pixels. In particular, sense circuitry 25 may be configured to measure current from the organic light-emitting diode of a selected display pixel.
Another issue that negatively impacts the accuracy of current sensing operations is lateral leakage current between anode terminals of adjacent organic light-emitting diodes.
Ideally, adjacent diodes in display 14 operate independently. In practice, the presence of common layers such as hole layer 62 present an opportunity for leakage current from one diode to flow laterally into an adjacent diode, thereby potentially disrupting the adjacent diode. For example, there is a possibility that the process of applying a drive current between anode 42-1 and cathode 54 will give rise to lateral leakage current through hole layer 62 (e.g., a current from anode 42-1 to anode 42-2), as indicated by leakage current path 400.
The examples of layers included between the anodes 42 and the cathode 54 in
In the example of
In accordance with an embodiment, a display pixel 22 that is configured to mitigate both the residue current and the lateral leakage current issues during current sensing operations is shown in
Transistor 514 may be coupled between column line 23 (e.g., a shared path on which a reference voltage Vref is provided to each pixel 22 along a given column) and the gate of drive transistor 512. The gate terminal of drive transistor 512 is marked as Node2 in
Transistor 516 may be coupled between column line 26 (e.g., a data line that is coupled to column driver circuitry 20) and the source terminal of drive transistor 512. Transistor 516 has a gate terminal that receives scan control signal SCAN2 via second scan control line 28-2 and is selectively turned on to load a data signal into pixel 22. Transistor 516 is therefore sometimes referred to as a data loading transistor.
Transistor 518 may have a gate terminal that receives emission control signal EM, a drain terminal that is coupled to the anode terminal of diode 500 (marked as Node3 in
In the arrangement of
Current sensing therefore requires turning on the data loading transistor. In conventional display pixels, the data/sensing line would typically be electrically connected to the anode terminal of the light-emitting diode. In such cases, the residue current from the previous frame and lateral leakage current from an adjacent pixel will affect the current that is sensed through the data loading transistor. By interposing emission control transistor 510 between the current sensing node (i.e., Node1) and the anode terminal of diode 500 (i.e., Node3), the current sensing node is decoupled from diode 500 during current sensing operations (e.g., by turning off drive transistor 510 during current sensing operations). In other words, the problems illustrated in
With one suitable arrangement, which is sometimes described herein as an example, the channel region (active region) in some thin-film transistors on display 14 is formed from silicon (e.g., silicon such as polysilicon deposited using a low temperature process, sometimes referred to as “LTPS” or low-temperature polysilicon), whereas the channel region in other thin-film transistors on display 14 is formed from a semiconducting oxide material (e.g., amorphous indium gallium zinc oxide, sometimes referred to as “IGZO”). If desired, other types of semiconductors may be used in forming the thin-film transistors such as amorphous silicon, semiconducting oxides other than IGZO, etc. In a hybrid display configuration of this type, silicon transistors (e.g., LTPS transistors) may be used where attributes such as switching speed and good drive current are desired (e.g., for gate drivers in liquid crystal diode displays or in portions of an organic light-emitting diode display pixel where switching speed is a consideration), whereas oxide transistors (e.g., IGZO transistors) may be used where low leakage current is desired (e.g., in liquid crystal diode display pixels and display driver circuitry) or where high pixel-to-pixel uniformity is desired (e.g., in an array of organic light-emitting diode display pixels). Other considerations may also be taken into account (e.g., considerations related to power consumption, real estate consumption, hysteresis, etc.). Oxide transistors such as IGZO thin-film transistors are generally n-channel devices (i.e., NMOS transistors). Silicon transistors can be fabricated using p-channel or n-channel designs (i.e., LTPS devices may be either PMOS or NMOS). Combinations of these thin-film transistor structures can provide optimum performance.
In the example of
Since emission control transistor 510 is a p-channel transistor, the associated emission control signal EM is an active-low signal. In other words, p-channel transistor 510 is turned on by asserting signal EM (i.e., by driving EM low) and is turned off by deasserting signal EM (i.e., by driving EM high). Prior to time t1, only signal EM is asserted (e.g., active-low emission control signal EM is driven low to logic “0”) while all other scan control signals are deasserted (e.g., the SCAN1 active-high signals are driven to logic “0” while the SCAN2 active-low signals are driven to logic “1”). The period during which signal EM is asserted may be referred to as the emission period or the emission phase. At time t1, signal EM is deasserted to turn off emission control transistor 510. Since signal EM also controls anode reset transistor 518, driving signal EM high at time t1 turns on transistor 518 and resets Node3 to ground voltage VSSEL. The entire time period during which EM is driven high (i.e., from time t1 to t9) may therefore sometimes be referred to as an anode reset period/phase.
At time t2, scan signal SCAN1_ODD may be asserted to turn on transistor 514 in the odd row. Since transistor 514 is an n-channel transistor, signal SCAN1 controlling transistor 514 is an active-high signal (i.e., asserting SCAN1 drives SCAN1 to logic “1”). Activating transistor 514 in the odd row may allow the gate of the corresponding drive transistor 512 to be set to the reference voltage level Vref. At time t3, scan signal SCAN1_EVEN may be asserted to turn on transistor 514 in the even row. Activating transistor 514 in the even row may allow the gate of the corresponding drive transistor 512 to be set to the reference voltage level Vref.
At time t4, scan signal SCAN2_ODD may be asserted to turn on transistor 516 in the odd row. Since transistor 516 is an p-channel transistor, signal SCAN2 controlling transistor 516 is an active-low signal (i.e., asserting SCAN2 drives SCAN2 to logic “0”). Activating transistor 516 in the odd row may allow a data signal presented along line 26 to be loaded into the corresponding display pixel (e.g., the data signal may be loaded onto Node1). The value of the data signal at the falling edge of signal SCAN2_ODD (at around time t6) determines what is actually loaded into the display pixel. The period of time during which data is loaded into pixel 22 may be referred to as the data programming period or the data writing phase. The duration of time that the data signal should be held constant for that row is indicated as one unit programming time 1.0 H.
At time t5, scan signal SCAN2_EVEN may be asserted to turn on transistor 516 in the even row. Activating transistor 516 in the even row may allow a data signal presented along line 26 to be loaded into the corresponding display pixel. The value of the data signal at the falling edge of signal SCAN2_EVEN (at around time t8) determines what is actually loaded into the display pixel.
Signal SCAN2_ODD may be deasserted (i.e., driven high) right after time t6, which ends the data programming phase for the odd row. Signal SCAN2_EVEN may be deasserted (i.e., driven high) at time t8, which ends the data programming phase for the even row. At time t9, signal EM is driven low to resume the emission period. During the emission phase, current will flow through transistors 510 and 512 and light-emitting diode 500, where the magnitude of the current is dependent on the voltage stored across capacitor Cst1. The amount of current will affect the actual luminance of light that is emitted from diode 500.
The technical advantages and improvements to the operation of the display are illustrated in
In the example of
At time t1, signal EM is deasserted to turn off emission control transistor 510. At time t1, signal SCAN3 is also asserted (i.e., driven low) to turn on anode reset transistor 800, thereby resetting anode terminal Node3 to ground voltage VSSEL. Signal SCAN3 may therefore sometimes be referred to as an anode reset control signal.
At time t2, anode reset control signal SCAN3 may be deasserted (i.e., driven back up high) and active-high scan signal SCAN1_ODD may be asserted to turn on transistor 514 in the odd row. Activating transistor 514 in the odd row may allow the gate of the corresponding drive transistor 512 to be set to the reference voltage level Vref. At time t3, scan signal SCAN1_EVEN may be asserted to turn on transistor 514 in the even row. Activating transistor 514 in the even row may allow the gate of the corresponding drive transistor 512 to be set to the reference voltage level Vref.
At time t4, active-low scan signal SCAN2_ODD may be asserted to turn on transistor 516 in the odd row. Activating transistor 516 in the odd row may allow a data signal supplied along line 26 to be loaded into the corresponding display pixel (e.g., the data signal may be loaded onto Node1). The value of the data signal at the falling edge of signal SCAN2_ODD (at around time t6) determines what is actually loaded into display pixel 22.
At time t5, active-low scan signal SCAN2_EVEN may be asserted to turn on transistor 516 in the even row. Activating transistor 516 in the even row may allow a data signal presented along line 26 to be loaded into the corresponding display pixel. The value of the data signal at the falling edge of signal SCAN2_EVEN (at around time t8) determines what is actually loaded into the display pixel.
Active-low signal SCAN2_ODD may be deasserted (i.e., driven high) right after time t6, which ends the data programming phase for the odd row. Active-low signal SCAN2_EVEN may be deasserted (i.e., driven high) at time t8, which ends the data programming phase for the even row. At time t9, signal EM is driven low to resume the emission period. During the emission phase, current will flow through transistors 510 and 512 and light-emitting diode 500, where the magnitude of the current is dependent on the voltage stored across capacitor Cst1. The amount of current will affect the actual luminance of light that is emitted from diode 500.
In the example of
At time t1, signal EM is deasserted to turn off emission control transistor 510. At time t1, signal AR is also asserted (i.e., driven low) to turn on anode reset transistor 800, thereby resetting anode terminal Node3 to ground voltage VSSEL. In contrast to the operation of
At time t2, active-high scan signal SCAN1_ODD may be asserted to turn on transistor 514 in the odd row. Activating transistor 514 in the odd row may allow the gate of the corresponding drive transistor 512 to be set to the reference voltage level Vref. At time t3, scan signal SCAN1_EVEN may be asserted to turn on transistor 514 in the even row. Activating transistor 514 in the even row may allow the gate of the corresponding drive transistor 512 to be set to the reference voltage level Vref.
At time t4, active-low scan signal SCAN2_ODD may be asserted to turn on transistor 516 in the odd row. Activating transistor 516 in the odd row may allow a data signal supplied along line 26 to be loaded into the corresponding display pixel (e.g., the data signal may be loaded onto Node1). The value of the data signal at the falling edge of signal SCAN2_ODD (at around time t6) determines what is actually loaded into display pixel 22.
At time t5, active-low scan signal SCAN2_EVEN may be asserted to turn on transistor 516 in the even row. Activating transistor 516 in the even row may allow a data signal presented along line 26 to be loaded into the corresponding display pixel. The value of the data signal at the falling edge of signal SCAN2_EVEN (at around time t8) determines what is actually loaded into the display pixel.
Active-low signal SCAN2_ODD may be deasserted (i.e., driven high) right after time t6, which ends the data programming phase for the odd row. Active-low signal SCAN2_EVEN may be deasserted (i.e., driven high) at time t8, which ends the data programming phase for the even row. At time t9, anode reset signal is deasserted and signal EM is driven low to resume the emission period. During the emission phase, current will flow through transistors 510 and 512 and light-emitting diode 500, where the magnitude of the current is dependent on the voltage stored across capacitor Cst1. The amount of current will affect the actual luminance of light that is emitted from diode 500.
In the example of
In accordance with an embodiment, in-frame sensing (IFS) operations may be performed at selected rows in the display pixel array. In
At time t4, signal SCAN2 may be pulsed low to temporarily activate data-loading/current-sensing transistor 516. During this time, sense circuitry 25 may be configured to sense the actual current flowing through transistors 512 and 516 and onto sensing line 26 (as indicated by the current sensing path 700 shown in
At time t5, active-high signal SCAN1 may again be pulsed high to temporarily turn on gate setting transistor 514 (i.e., to drive Node2 to reference voltage Vref). At time t6, active-low signal SCAN2 may again be pulsed low to temporarily turn on data loading transistor 516. During this time, the desired emission data may be loaded into display pixel 22. After the reprogramming pixel 22 with the actual image data, signal SCAN1 may be driven low. At time t7, active-low emission signal EM is asserted (i.e., driven low) to restart the emission phase.
The in-frame sensing operation shown in
In accordance with an embodiment, a display pixel is provided that includes an organic light-emitting diode, a drive transistor coupled in series with the organic light-emitting diode, the drive transistor has a drain terminal, a gate terminal, and a source terminal, a data line, a data loading transistor coupled between the data line and the source terminal of the drive transistor, the data loading transistor is configured to write data from the data line into the display pixel during data loading operations and to output sensing current onto the data line during current sensing operations, and an emission control transistor interposed between the drive transistor and the organic light-emitting diode, the emission control transistor is configured to decouple the organic light-emitting diode from the drive transistor during the current sensing operations.
In accordance with another embodiment, the emission control transistor is turned off during the current sensing operations to prevent residue current and lateral leakage current at the organic light-emitting diode from contributing to the sensing current.
In accordance with another embodiment, the display pixel includes a gate setting transistor coupled to the gate terminal of the drive transistor, the gate setting transistor is configured to provide a reference voltage onto the gate terminal of the drive transistor.
In accordance with another embodiment, the display pixel includes a storage capacitor having a first terminal coupled to the gate terminal of the drive transistor and a second terminal coupled to the source terminal of the drive transistor.
In accordance with another embodiment, the display pixel includes an anode resetting transistor coupled in parallel with the organic light-emitting diode.
In accordance with another embodiment, the emission control transistor has a gate terminal configured to receive an emission control signal, and the anode resetting transistor has a gate terminal configured to receive the emission control signal.
In accordance with another embodiment, the emission control transistor has a gate terminal configured to receive an emission control signal, and the anode resetting transistor has a gate terminal configured to a scan control signal that is different than the emission control signal.
In accordance with another embodiment, the emission control signal and the scan control signal are shared between at least two adjacent rows of display pixels.
In accordance with another embodiment, the drive transistor and the gate setting transistor are semi-conducting oxide transistors, and at least one other transistor in the display pixel is not a semi-conducting oxide transistor.
In accordance with another embodiment, all of the transistors in the display pixel are semi-conducting oxide transistors.
In accordance with an embodiment, a method of operating a display pixel is provided that includes a drive transistor, an emission control transistor, and an organic light-emitting diode couple in series, the method includes turning off the emission control transistor to decouple the drive transistor from the organic light-emitting diode, and while the emission control transistor is turned off, turning on a data loading transistor to output sensing current onto a corresponding data line, the sensing current flows through the drive transistor, and the emission control transistor prevents residue current and lateral leakage current at the organic light-emitting diode from contributing to the sensing current.
In accordance with another embodiment, the method includes turning on an anode reset transistor to reset the organic light-emitting diode.
In accordance with another embodiment, the method includes providing an emission control signal to control both the emission control transistor and the anode reset transistor.
In accordance with another embodiment, the method includes providing an emission control signal to the emission control transistor, and providing a scan control signal to the anode reset transistor, the emission control signal and the scan control signal are different.
In accordance with another embodiment, the method includes using the data loading transistor to program sensing data into the display pixel, sensing background noise from the display pixel while the data loading transistor is turned off, and after outputting the sensing current onto the data line, using the data loading transistor to program the display pixel with emission data, the emission data is different than the sensing data.
In accordance with an embodiment, display circuitry is provided that includes compensation circuitry configured to compensate for variations within the display circuitry and a display pixel that includes a drive transistor having a drain terminal, a gate terminal, and a source terminal a data loading transistor coupled to the source terminal of the drive transistor, the data loading transistor is configured to output a sensing current from the drive transistor to the compensation circuitry an organic light-emitting diode coupled in series with the drive transistor and an emission control transistor coupled between the drive transistor and the organic light-emitting diode, the emission control transistor is configured to electrically isolate the organic light-emitting diode from the data loading transistor while the data loading transistor is outputting the sensing current to the compensation circuitry.
In accordance with another embodiment, the display circuitry includes an additional display pixel that includes an additional emission control transistor and an additional data loading transistor, the emission control transistor and the additional emission control transistor receive the same emission control signal, and the data loading transistor and the additional data loading transistor receive different scan control signals.
In accordance with another embodiment, the drive transistor in the display pixel is implemented as a semi-conducting oxide transistor to reduce leakage current, and at least one other transistor in the display pixel is implemented as a silicon transistor to increase performance.
In accordance with another embodiment, the data loading transistor is turned off while the compensation circuitry is configured to sense background noise, and the compensation circuitry is further configured to compare the sensing current to the background noise.
In accordance with another embodiment, the data loading transistor is configured to reprogram emission data into the display pixel after sensing the background noise.
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.
This application claims priority to U.S. patent application No. 62/595,390, filed on Dec. 6, 2017, which is hereby incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2018/053589 | 9/28/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62595390 | Dec 2017 | US |
