Pixel Reset Voltage for OLED Hysteresis Reduction
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Solution Overview
Problem
Electronic displays suffer from slow response times due to hysteresis, which affects perceived image quality by causing ghost images and mura effects, especially in current-driven displays like OLEDs when displaying low luminance images or in short persistent modes.
Innovation Solution
The electronic display resets display pixels by applying a target voltage during a non-emission period to relax them and overwrite previous image frame data, reducing hysteresis by controlling light emission through programmed emission and non-emission periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If display pixels are controlled to emit light for a target emission period to achieve desired luminance, then the display can show image frames at correct brightness levels, but hysteresis causes slow response time and ghost images in subsequent frames
Solution Approach 1:
The patent applies a reset voltage to display pixels before they emit light for the target emission period. This preliminary action clears residual charge and resets the pixel state, preventing hysteresis effects from previous frames while ensuring the pixel is ready to accurately display the current frame's luminance requirements.
Solution Approach 2:
The patent changes the voltage parameter applied to display pixels by introducing a reset voltage level that is distinct from the programming voltage and emission voltage. This parameter change resets the pixel's internal state, eliminating hysteresis and enabling faster response time without compromising the ability to control luminance during the emission period.
2Loss of time
If display pixels are reset by applying target voltage during non-emission period to overwrite previous image frame data, then hysteresis is reduced and response time improves, but the display period must be divided into emission and non-emission periods
Solution Approach 1:
The patent implements periodic reset actions during the non-emission periods between frame displays. By systematically applying reset voltages during these regular intervals, the display maintains fast response times across consecutive frames while using a straightforward periodic control scheme that manages complexity through rhythm rather than complexity.
Solution Approach 2:
The patent ensures continuous useful action by utilizing the non-emission period (which would otherwise be idle time) for the beneficial purpose of resetting display pixels. This transforms a potentially wasted time interval into a productive reset phase, maintaining fast response times without requiring additional time beyond the existing display period structure.
3Illumination intensity
If current-driven displays like OLED are used to achieve high image quality, then luminance control is improved, but hysteresis effects are amplified especially during low luminance display and short persistent modes
Solution Approach 1:
The patent applies preliminary anti-action by using reset voltages to counteract the hysteresis effects that current-driven displays naturally produce. This preemptive measure neutralizes the problematic residual charge buildup before it can significantly degrade image quality or response time, particularly during low luminance display and short persistent modes where hysteresis is most pronounced.
Data Source
AI summary
An electronic device includes processors that generate image data. The electronic device also includes an electronic display that displays the image data over a first frame duration by programming a first row of display pixels with the image data. The electronic display also displays the image data over the first frame duration by causing the first row of display pixels to emit light for an emission duration that is based at least in part on a first luminance of the image data. The electronic display further displays the image data over the first frame duration by resetting the first row of pixels before an end of the first frame duration.