Pixel Circuit Design for AMOLED Display Uniformity
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Solution Overview
Problem
The existing manufacturing processes for TFTs in AMOLED displays, such as ELA and doping, fail to ensure uniformity, leading to threshold voltage deviations and poor display uniformity due to non-uniform brightness across pixels.
Innovation Solution
A pixel circuit design comprising a pre-storage sub-circuit, driving sub-circuit, reset sub-circuit, and light emitting control sub-circuit, which maintains and provides data voltages during reset and light emitting phases, decouples and couples the driving sub-circuit from the light emitting device, and uses reference voltages to reduce the influence of threshold voltage on display uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional TFT manufacturing processes (ELA and doping) are used, then production efficiency is maintained, but display uniformity deteriorates due to threshold voltage deviations
Solution Approach 1:
The pixel circuit is divided into multiple functional sub-circuits: a pre-storage sub-circuit for maintaining and pre-storing data voltages, a driving sub-circuit for driving the light emitting device, a reset sub-circuit for resetting node voltages, and a light emitting control sub-circuit for controlling the light emitting phase. This segmentation allows each sub-circuit to perform its function independently, improving display uniformity by reducing threshold voltage impact while maintaining manageable complexity through modular design
Solution Approach 2:
The pre-storage sub-circuit performs preliminary actions by maintaining the data voltage of the current frame during the reset phase and pre-storing the data voltage of the next frame during the light emitting phase. This preliminary preparation ensures that accurate voltage levels are ready before driving operations, reducing the impact of threshold voltage deviations and improving display uniformity without requiring complex manufacturing processes
2Manufacturing precision
If threshold voltage compensation is implemented, then display uniformity improves, but circuit complexity increases
Solution Approach 1:
The reset sub-circuit automatically resets the voltage of the second node to the reference voltage during the reset phase, and the pre-storage sub-circuit automatically maintains and pre-stores data voltages based on phase timing. This self-service mechanism provides threshold voltage compensation without requiring external intervention or complex control logic, improving uniformity while keeping the circuit structure manageable
Solution Approach 2:
The circuit operates in periodic phases including reset phase, data providing phase, and light emitting phase. During each reset phase, the reset sub-circuit periodically resets node voltages to reference levels. This periodic resetting action continuously compensates for threshold voltage deviations throughout operation, maintaining display uniformity through rhythmic correction rather than complex continuous control
3Manufacturing precision
If data voltage is maintained during reset phase, then display uniformity improves, but power consumption increases
Solution Approach 1:
The light emitting control sub-circuit extracts and isolates the light emitting function from the driving sub-circuit by controlling coupling and decoupling. During the reset phase and data providing phase, the driving sub-circuit is decoupled from the light emitting device, eliminating unnecessary power consumption while the pre-storage sub-circuit maintains data voltages. This selective coupling reduces power consumption while preserving display uniformity through proper voltage management during active phases
4Use of energy by moving object
If driving sub-circuit is decoupled during data providing phase, then power consumption reduces, but control complexity increases
Solution Approach 1:
The light emitting control sub-circuit uses periodic coupling and decoupling actions synchronized with display phases. During reset and data providing phases, the driving sub-circuit is decoupled to reduce power consumption. During light emitting phase, coupling is enabled. This periodic control pattern, driven by phase timing signals, manages power consumption through simple on/off switching rather than complex continuous control, keeping the control logic manageable while achieving energy savings
Data Source
AI summary
The present disclosure provides a pixel circuit, a pixel array, a display device, and a driving method. The pixel circuit includes a pre-storage sub-circuit, a driving sub-circuit, a first reset sub-circuit, and a light emitting control sub-circuit. The pre-storage sub-circuit is used to maintain and provide a data voltage of a current frame image, and pre-store a data voltage of a next frame image. The driving sub-circuit is used to drive a light emitting device to emit light. The first reset sub-circuit is used to be turned on during the reset phase to transmit the reference voltage to the driving sub-circuit and turned off during a time period other than the reset phase. The light emitting control sub-circuit is used to control that the driving sub-circuit is coupled to or decoupled from the light emitting device.