Display Pixel Scan Segmentation for Low-Frequency Brightness Uniformity
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Solution Overview
Problem
Existing organic light-emitting display apparatuses face challenges in reducing brightness differences across various driving frequencies, which affects the display's uniformity and efficiency.
Innovation Solution
The implementation of a display apparatus with a pixel structure that includes oxide semiconductor transistors, where the driving frequency is adjusted by controlling the scan signals and data signals through a gate driving circuit, minimizing brightness differences across different driving frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the driving frequency is reduced to save power, then power consumption is reduced, but brightness uniformity deteriorates
Solution Approach 1:
The scan period is divided into multiple sub-periods (first scan period, second scan period, third scan period) with different operations. During the first scan period, normal data writing occurs. During the second scan period, leakage current compensation is performed by adjusting the gate voltage of the driving transistor. This segmentation allows the system to maintain brightness uniformity even at reduced driving frequencies by periodically compensating for transistor leakage effects that become more pronounced at lower frequencies.
2Loss of energy
If the driving frequency is reduced to increase power efficiency, then power efficiency is improved, but display uniformity deteriorates
Solution Approach 1:
The patent implements preliminary leakage current compensation by performing compensation operations in the second scan period before the actual display refresh. The gate voltage of the driving transistor is adjusted in advance to compensate for expected leakage effects, ensuring that when the display operates at reduced frequencies, the brightness remains uniform across all pixels. This preliminary action prevents the accumulation of leakage errors that would otherwise degrade display uniformity.
3Object-generated harmful factors
If oxide semiconductor transistors are used to reduce leakage current, then leakage current is reduced, but brightness difference across driving frequencies persists
Solution Approach 1:
The patent implements a feedback mechanism where the system monitors and compensates for leakage current effects dynamically. During the second scan period, the gate voltage of the driving transistor is adjusted based on the measured or estimated leakage current characteristics. This feedback loop ensures that even with oxide semiconductor transistors that have lower but non-zero leakage, the brightness remains consistent across different driving frequencies by continuously compensating for leakage variations.
Data Source
AI summary
A display apparatus includes a pixel part including a plurality of pixels, and a gate driving circuit. Each of the plurality of pixels is driven in one first scan period and one or more second scan periods during one frame in a driving mode driven at a first driving frequency lower than a maximum driving frequency.