Gate Driver Node Controller for Display Luminance Uniformity
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Solution Overview
Problem
Display devices experience deviations in gate signals due to threshold voltage variations of transistors, leading to luminance differences between pixels, resulting in horizontal stripe defects.
Innovation Solution
A display device with a gate driver that includes a node controller and an output unit, featuring transistors and capacitors to control and compensate the gate signal voltage, ensuring a stable transition from high to low levels and maintaining a consistent output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional gate driver is used without compensation circuitry, then the device complexity is low, but luminance uniformity deteriorates due to gate signal deviation
Solution Approach 1:
The patent implements a feedback mechanism where the gate signal output is fed back to control nodes (first and second control nodes) that regulate the gate signal generation. This closed-loop feedback compensates for threshold voltage variations in transistors, ensuring consistent gate signal output and uniform luminance across pixels while managing device complexity through targeted control.
Solution Approach 2:
The patent changes the voltage levels at control nodes dynamically during operation. The first control node and second control node are regulated to different voltage levels (first control voltage and second control voltage) to compensate for transistor threshold variations. This parameter adjustment ensures stable gate signal output despite manufacturing variations, improving luminance uniformity without requiring complete redesign of the gate driver.
2Reliability
If transistor threshold voltage variations are present, then manufacturing is easier, but gate signal stability deteriorates causing horizontal stripe defects
Solution Approach 1:
The feedback mechanism compensates for inherent transistor threshold voltage variations by continuously monitoring and adjusting control node voltages. This ensures stable gate signal output despite manufacturing variations, improving reliability without complicating the fabrication process.
Solution Approach 2:
The patent performs preliminary compensation by pre-establishing the feedback control mechanism that actively corrects threshold voltage effects before they can cause luminance deviations. The control nodes are regulated in advance to counteract expected variations, ensuring stable gate signals from the outset.
3Speed
If gate signal transitions are made rapid, then switching speed is improved, but signal stability deteriorates due to threshold voltage effects
Solution Approach 1:
The feedback control mechanism ensures that rapid gate signal transitions maintain accuracy by continuously adjusting control node voltages. This allows fast switching while compensating for threshold voltage effects that would otherwise cause signal deviation, achieving both speed and reliability.
Data Source
AI summary
A display device includes a display panel including gate lines and pixels connected to the gate lines, and a gate driver including plural stages providing gate signals to the gate lines. A first stage among the stages includes a node controller including an input terminal and configured to control a voltage of a first control node and a voltage of a second control node, and an output unit connected to a first gate power source line and configured to output a first gate power source voltage of the first gate power source line as a gate signal through an output terminal in response to the voltage of the first control node. The node controller includes a first auxiliary transistor connected in the form of a diode between the input terminal and the second control node and a boosting capacitor connected between the second control node and the output terminal.