Pixel Circuit Compensation for Display Power and Quality
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Solution Overview
Problem
Display devices face challenges in reducing power consumption while maintaining high display quality, especially when displaying high-resolution or stereoscopic images, as lowering driving frequency leads to image quality deterioration due to changes in hysteresis characteristics of driving transistors.
Innovation Solution
The implementation of a pixel structure with specific transistor configurations and timing control, including oxide semiconductor transistors, to secure a compensation period and prevent hysteresis-related quality deterioration, allowing for efficient power management across various frame frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the driving frequency is lowered to reduce power consumption, then power consumption is reduced, but display quality deteriorates due to hysteresis characteristics of driving transistors
Solution Approach 1:
The patent implements a compensation period before the emission period during which the compensation transistor is turned on to compensate for threshold voltage changes in the driving transistor. This preliminary action ensures that hysteresis-related display quality issues are prevented before image display begins, allowing lower driving frequencies to be used without sacrificing display quality.
Solution Approach 2:
The patent introduces periodic compensation cycles within each frame period, where the compensation transistor is periodically activated during compensation periods. This periodic action allows the system to maintain display quality at lower driving frequencies by regularly correcting threshold voltage drift without requiring continuous high-frequency operation.
2Use of energy by stationary object
If the driving frequency is lowered to reduce power consumption, then power consumption is reduced, but flicker and afterimages occur
Solution Approach 1:
The compensation period is implemented as a preliminary action before each emission period, where threshold voltage compensation is performed in advance. This prevents the accumulation of hysteresis effects that would otherwise cause flicker and afterimages at lower driving frequencies, while still allowing power consumption to be reduced through lower operating frequencies.
3Device complexity
If a compensation period is not sufficiently secured, then device complexity is reduced, but threshold voltage compensation is insufficient leading to display quality deterioration
Solution Approach 1:
The patent segments the frame period into distinct compensation periods and emission periods, with the compensation period dedicated to threshold voltage compensation and the emission period dedicated to image display. This temporal segmentation allows sufficient compensation time to be allocated without requiring additional hardware complexity, maintaining display quality while keeping the device structure relatively simple.
Data Source
AI summary
A pixel includes: a light emitting element; a first transistor generating a driving current flowing from a first power line to a second power line; a second transistor being turned on in response to a fourth scan signal; a third transistor being turned on in response to a second scan signal; a fourth transistor being turned on in response to a first scan signal; a fifth transistor being turned on in response to a third scan signal; a sixth transistor being turned off in response to a first emission control signal; a first capacitor; and a second capacitor. A period in which the second transistor is turned on and a period in which the third transistor is turned on do not overlap with each other.