Electronic Devices Having Displays With Compensation for Oxide Transistor Threshold Voltage

    公开(公告)号:US20200243012A1

    公开(公告)日:2020-07-30

    申请号:US16283481

    申请日:2019-02-22

    Applicant: Apple Inc.

    Abstract: A display may have an array of organic light-emitting diode display pixels. Each display pixel may include a drive transistor coupled in series with one or more emission transistors and a respective organic light-emitting diode (OLED). A semiconducting-oxide transistor may be coupled between a drain terminal and a gate terminal of the drive transistor to help reduce leakage during low-refresh-rate display operations. To compensate for variations in the threshold voltage of the semiconducting-oxide transistor, the magnitude of a high voltage level of a scan control signal provided to the gate terminal of the semiconducting-oxide transistor may be adjusted. Sensing circuitry may be used to sense a display current while displaying a calibration image. The sensed display current may be compared to an expected display current associated with the calibration image. Processing circuitry may update the high voltage level based on the actual display current compared to the expected display current.

    Digital VCOM compensation for reducing display artifacts

    公开(公告)号:US10580381B2

    公开(公告)日:2020-03-03

    申请号:US15842364

    申请日:2017-12-14

    Applicant: Apple Inc.

    Abstract: The present disclosure relates to systems and methods of accounting for the kickback voltage in an LCD display. For example, a method may include obtaining, via a processor, a difference between a nominal voltage of a common electrode of a display and a measured voltage of the common electrode. The processor may obtain image data associated with an image to be displayed on the display. The processor may adjust the image data of a pixel of the display based on the difference. The processor may output an image signal indicative of the adjusted image data to a pixel electrode of the pixel.

    Spatial temporal phase shifted polarity aware dither

    公开(公告)号:US10319279B2

    公开(公告)日:2019-06-11

    申请号:US15438448

    申请日:2017-02-21

    Applicant: Apple Inc.

    Abstract: This application relates to performing certain dithering processes to eliminate display artifacts such as flicker, which can be caused by charge accumulation at the display. The dither process can be performed by a display controller that uses a group lookup method for identifying groups of dithering patterns that can be combined to expand a number of color values available to the display. The dither process can also be performed as a temporal process that incorporates groups of dithering patterns into frames and shifts a spatial arrangement of the groups of dithering patterns over a sequence of frames. Additionally, the dither process can incorporate counters that count the number of times a particular spatial arrangement of dithering patterns has been used in a sequence of frames in order that each spatial arrangement of dithering patterns will share an average count with other spatial arrangements over a sequence of frames.

    Digital compensation for V-gate coupling

    公开(公告)号:US10043472B2

    公开(公告)日:2018-08-07

    申请号:US14976853

    申请日:2015-12-21

    Applicant: Apple Inc.

    Abstract: A display device may include a source line that provides a data line signal to a pixel of the display device, a gate line that provides a gate signal to a switches associated with the pixel, and a voltage gate line disposed parallel to the source line and coupled to the gate line at a cross point node. The display device may also include a driver circuit that receives a pixel value to provide to the pixel, determines a compensation amount for the pixel value based on an expected kickback voltage present on the pixel due to a coupling effect between the source line and the voltage gate line, generates a compensated data line signal based on the compensation value and the pixel value, and provides the compensated data line signal to the pixel via the source line.

    THRESHOLD VOLTAGE HYSTERESIS COMPENSATION
    139.
    发明申请

    公开(公告)号:US20180090074A1

    公开(公告)日:2018-03-29

    申请号:US15701030

    申请日:2017-09-11

    Applicant: Apple Inc.

    Abstract: Electronic devices, storage medium containing instructions, and methods pertain to determining a target boosted threshold voltage level based at least in part on a target emission threshold voltage level. Using the determined target boosted threshold voltage level, a light emitting diode (LED)-controlling transistor is submitted to voltage stress to boost a threshold voltage of the transistor to the target boosted threshold voltage level during a first portion of a refresh period between first and second emission periods. During a second portion of the refresh period, the voltage stress is de-asserted to settle the threshold voltage to a target emission threshold voltage level for the second emission period. After the voltage is settled, the LED-controlling transistor is driven based at least in part on the target emission threshold voltage level.

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