Scan Driver Stage with Multiple Output Buffers
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Solution Overview
Problem
Display devices face challenges in efficiently driving transistors due to constant current flow and transistor deterioration when a specific transistor is always maintained in a turned-on state, leading to increased power consumption and reduced efficiency.
Innovation Solution
A stage and scan driver configuration that eliminates the need for an inverter, reducing the number of transistors and capacitors, and avoids the requirement for a dummy circuit, allowing for controlled voltage management without constantly maintaining a transistor in a turned-on state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inverter is used to control the node voltage in the stage, then the voltage control function is achieved, but the number of transistors increases and a specific transistor must be always maintained in a turned-on state causing constant current flow and characteristic deterioration
Solution Approach 1:
The patent removes the inverter from the stage circuit, extracting the problematic component that caused constant current flow and transistor deterioration. The voltage control function is achieved through alternative means (direct control of driving node voltage) without requiring the inverter structure, thereby reducing the number of transistors while maintaining the essential voltage control capability.
Solution Approach 2:
The patent transitions from a static configuration where a transistor must be always turned on to a dynamic configuration where transistors are controlled to turn on and off as needed. By directly controlling the driving node voltage through the carry signal and control signals, the circuit achieves voltage control without requiring any transistor to remain permanently conductive, thus eliminating constant current flow.
2Reliability
If an inverter is used in the stage configuration, then voltage control is achieved, but power consumption increases due to constant current flow
Solution Approach 1:
The inverter is extracted from the circuit, removing the source of constant current flow. The voltage control function is maintained through direct control of the driving node by the carry signal and control signals, eliminating the continuous power consumption associated with keeping a transistor permanently turned on in the inverter configuration.
Solution Approach 2:
The patent implements periodic control of the driving node voltage through clocked carry signals and control signals (first, second, and third control signals). This periodic action allows the transistor to turn on only when needed for voltage transition, rather than remaining continuously conductive as in the inverter configuration, thereby reducing power consumption while maintaining voltage control capability.
3Reliability
If a dummy circuit is included in the stage, then circuit functionality is ensured, but the number of transistors and capacitors increases
Solution Approach 1:
The patent removes the dummy circuit from the stage configuration. The essential circuit functionality is maintained through the optimized transistor arrangement and control signal mechanism, where the carry signal and control signals directly manage the driving node voltage without requiring additional dummy transistors or capacitors, thus reducing device complexity while preserving functionality.
Solution Approach 2:
The patent makes the existing transistors multi-functional by having them perform both voltage control and signal transmission functions. The transistors controlled by the carry signal and control signals serve multiple purposes: controlling the driving node voltage, transmitting the scan signal, and enabling the sensing function, thereby eliminating the need for separate dummy circuits while maintaining all necessary functionalities.
Data Source
AI summary
A stage and a scan driver having the same. The stage outputs a scan signal and a sensing signal to a scan line and a sensing line, respectively. The stage includes a first controller configured to control a voltage of a sensing node and a driving node based on first to third control signals and a carry signal of the stage and another stage connected to the stage, a second controller configured to control a voltage of an inversion driving node based on a first carry clock signal, the voltage of the driving node, and the third control signal, and a first output buffer configured to output a second carry clock signal or a second low potential power as the carry signal in correspondence with the voltage of the driving node and the inversion driving node.