Shift Register Pull-Down Control for Stable Display Signals
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Solution Overview
Problem
The reliability of gate and emission drivers in display apparatuses is compromised due to unstable low levels of output signals in shift registers, leading to display quality deterioration and transistor malfunction.
Innovation Solution
A shift register design incorporating a pull up switching element, a pull down switching element, and diode-connected control switching elements to stabilize the control signal for the pull down switching element, ensuring stable output signal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional shift register circuit is used, then the device complexity is low, but the reliability of output signal levels deteriorates
Solution Approach 1:
The patent introduces a diode-connected switching element as an intermediary component between the control signal source and the pull-down switching element. This intermediary stabilizes the control signal by preventing voltage fluctuations and ensuring a stable reference level, thereby improving output signal stability without requiring fundamental changes to the shift register architecture.
Solution Approach 2:
The patent segments the control mechanism by separating the control signal path into distinct functional parts: the original control signal line, the diode-connected stabilizing element, and the pull-down switching element. This segmentation allows each component to perform its specific function optimally, with the diode-connected element dedicated solely to signal stabilization.
2Reliability
If the control signal level is unstable, then the device complexity remains simple, but the display quality deteriorates
Solution Approach 1:
The diode-connected switching element acts as a signal quality intermediary, filtering out instability from the control signal before it reaches the pull-down switching element. This ensures that the control signal maintains a stable voltage level, which is critical for achieving consistent display quality in OLED panels.
Solution Approach 2:
The patent implements beforehand cushioning by pre-stabilizing the control signal using the diode-connected element before it is applied to control the pull-down switching element. This preventive measure ensures that voltage fluctuations are eliminated in advance, preventing display quality deterioration before it occurs.
3Reliability
If additional control switching elements are added, then the output signal stability improves, but the manufacturing complexity increases
Solution Approach 1:
The diode-connected switching element is designed to serve multiple functions: it stabilizes the control signal level, provides a reference voltage for the pull-down switching element, and prevents signal fluctuations. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in manufacturing complexity.
Solution Approach 2:
The patent merges the stabilization function into an existing switching element by configuring it in a diode connection, rather than adding a completely separate component. This merging approach allows the same physical component to perform both signal switching and voltage stabilization functions, simplifying the manufacturing process.
Data Source
AI summary
A shift register includes a plurality of stages. At least one of the stages is configured to receive an input signal, a first clock signal, a second clock signal, a first power voltage and a second power voltage and to output an output signal. The at least one of the stages includes a pull up switching element connected between a first power voltage terminal configured to receive the first power voltage and an output terminal configured to output the output signal, a pull down switching element connected between a second power voltage terminal configured to receive the second power voltage and the output terminal, a first pull down control switching element connected to a control electrode of the pull down switching element and a second pull down control switching element connected to the first power voltage terminal and the control electrode of the pull down switching element.