Shift Register Gate-Shading Circuit for Display Panel Voltage Stability
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Solution Overview
Problem
In advanced Gate on Array (GOA) processes, the integration of gate-driving circuits on display panels to reduce bezel size poses a challenge in implementing a gate-shading function efficiently without additional circuitry, as existing solutions rely on separate gate driver ICs or complex gate-shading circuits to maintain consistent charging voltages and prevent flickering.
Innovation Solution
A gate-shading circuit within a shift register is implemented, utilizing multiple switches to control voltage levels and stabilize output signals, allowing for the generation of shading waveforms by pulling down voltages on gate and output terminals, and incorporating a voltage stabilizing circuit to maintain voltage stability when stages are not activated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate driver IC with gate-shading circuit is used, then charging voltage consistency is improved, but device complexity and area occupancy increase
Solution Approach 1:
The gate-shading circuit is merged with the shift register circuit by sharing the output transistor between the shift register function and the gate-shading function. The output transistor's drain serves as both the shift register output and the gate-shading circuit output, eliminating the need for separate gate driver IC and reducing overall circuit complexity while maintaining charging voltage consistency
Solution Approach 2:
The output transistor is designed to serve multiple functions: it acts as the output transistor for the shift register stage and simultaneously serves as the output transistor for the gate-shading circuit. This multi-functionality allows a single transistor to fulfill dual roles, reducing the total number of components needed in the system
2Reliability
If gate driver IC with gate-shading circuit is used, then charging voltage consistency is improved, but area occupancy increases
Solution Approach 1:
The gate-shading circuit is merged with the shift register circuit by sharing the output transistor between the shift register function and the gate-shading function. The output transistor's drain serves as both the shift register output and the gate-shading circuit output, eliminating the need for separate gate driver IC and reducing overall circuit complexity while maintaining charging voltage consistency
Solution Approach 2:
The output transistor is designed to serve multiple functions: it acts as the output transistor for the shift register stage and simultaneously serves as the output transistor for the gate-shading circuit. This multi-functionality allows a single transistor to fulfill dual roles, reducing the total number of components needed in the system
3Device complexity
If simple shift register without gate-shading is used, then device complexity is reduced, but flickering problem occurs due to inconsistent charging voltages
Solution Approach 1:
The gate-shading circuit is merged with the shift register circuit by sharing the output transistor between the shift register function and the gate-shading function. The output transistor's drain serves as both the shift register output and the gate-shading circuit output, eliminating the need for separate gate driver IC and reducing overall circuit complexity while maintaining charging voltage consistency
Solution Approach 2:
The gate-shading circuit proactively compensates for impedance variations by pre-adjusting the gate driving signal waveform before it reaches the pixel units. By forming a shading waveform that accounts for expected voltage drops across different positions, the circuit prevents flickering before it occurs rather than correcting it afterward
Data Source
AI summary
A shift register circuit and a shading waveform generating method are disclosed. The shift register circuit includes plural stages of shift registers. Each stage of the shift register includes an output transistor, an input unit and a gate-shading circuit. The output transistor is configured for generating an output signal of the stage of the shift register. The input unit is configured for controlling a voltage level on a gate terminal of the output transistor. The gate-shading circuit includes a first switch, a second switch and a third switch. The first switch is configured for outputting a control signal. The second switch is configured for pulling down the voltage level on the gate terminal of the output transistor according to the control signal. The third switch is configured for pulling down a level on an output terminal of the output transistor according to the control signal.