Shared Pull-Up Scan Driver for Narrow-Bezel Stable Displays
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Solution Overview
Problem
The increase in the size and arrangement area of scan and sensing drivers in display devices leads to a larger bezel area, affecting the display device's aesthetics and potentially degrading image quality due to unstable voltage levels in scan and sensing signals.
Innovation Solution
A scan driver design that reduces the number of stage circuits by sharing pull-up nodes and includes output control parts, carry output parts, and node voltage control parts to stabilize voltage levels, allowing multiple output circuits to operate efficiently and maintain stable signal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of stage circuits is increased to provide more scan output signals, then the scan driver can drive more scan signal lines, but the area of the non-display area (bezel area) increases
Solution Approach 1:
Multiple output circuits share a common pull-up node to reduce the total number of transistors required. Instead of each output circuit having its own dedicated pull-up transistor, the patent implements a shared pull-up node that serves multiple output circuits simultaneously, thereby reducing the overall circuit area in the non-display region.
Solution Approach 2:
The pull-up node is designed to serve multiple functions by being shared among multiple output circuits. This multi-functional design allows a single pull-up node to control multiple scan signal lines through different output circuits, increasing the adaptability of the scan driver without proportionally increasing the bezel area.
2Area of stationary object
If the pull-up node is shared by multiple output circuits to reduce bezel area, then the area is reduced, but the voltage level of the pull-up node becomes unstable
Solution Approach 1:
The patent implements a feedback mechanism where the actual voltage level of the shared pull-up node is monitored and used to dynamically adjust the gate voltage of the pull-up transistor. This closed-loop control ensures that despite multiple output circuits sharing the same pull-up node, the voltage level remains stable and within the required operating range.
Solution Approach 2:
The gate voltage of the pull-up transistor is made dynamic rather than fixed. By adjusting the gate voltage based on the actual operating conditions and voltage level requirements, the system can maintain stable operation of the shared pull-up node while serving multiple output circuits, thus stabilizing the voltage composition.
Data Source
AI summary
A scan driver includes a first scan driving circuit sequentially outputting gate scan signals to scan signal lines during an active period, wherein the first scan driving circuit includes: an n-th stage supplying a gate-on voltage to a pull-up node in response to a first gate control signal of a display driver circuit; output control parts sharing a pull-up node of the n-th stage and sequentially outputting the gate scan signals during an enable period in which the gate-on voltage is supplied to the pull-up node; at least one carry output part sharing the pull-up node of the n-th stage and outputting at least one carry signal during the enable period; and at least one node voltage control part controlling a voltage magnitude of the gate-on voltage charged to the pull-up node during the enable period in response to a pull-up control signal of the display driving circuit.