Shift Register Gate Drive Circuit Reliability
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Solution Overview
Problem
Existing shift registers for active matrix liquid crystal display devices face reliability issues due to component deterioration, particularly in the gate drive circuit, which affects the accuracy and longevity of the display device.
Innovation Solution
A shift register design that incorporates stages with a pull up drive section, a pull down drive section, and a maintaining section, utilizing two clock signals to generate and maintain gate signals, thereby reducing component deterioration and improving reliability by using AC pulse signals and a carry signal for control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional shift register is used in the gate drive circuit, then the display device can operate, but component deterioration occurs leading to reduced reliability
Solution Approach 1:
The patent applies periodic action by using AC pulse signals instead of DC signals to drive the shift register. The gate drive circuit switches between positive and negative voltage levels periodically, which prevents charge accumulation and reduces stress on components. This periodic voltage application extends component life while maintaining reliable operation of the display device.
2Reliability
If more switching members are used to improve reliability, then component deterioration is reduced, but the marginal size of the display panel increases
Solution Approach 1:
The patent merges multiple functions into fewer switching members. The dual-gate shift register structure allows a single stage to control multiple functions through its two gates, reducing the total number of switching members needed. This integration maintains reliability while minimizing the marginal size of the display panel.
Solution Approach 2:
The switching members in the proposed shift register are designed with multi-functionality. Each switching member can operate in different modes (e.g., as a drive transistor, a storage transistor, or a control element) depending on the operating phase. This universality reduces the overall count of switching members required, thereby reducing the marginal size while maintaining system reliability.
3Device complexity
If DC signals are used to drive the shift register, then the circuit is simple, but component deterioration occurs due to charge accumulation
Solution Approach 1:
The patent changes the voltage parameter from DC to AC pulse signals. By switching between positive and negative voltage levels, the system prevents charge accumulation that would occur with DC signals. This parameter change improves component reliability without significantly increasing circuit complexity, as the AC pulse generation can be achieved through simple capacitor coupling and inversion circuits.
Data Source
AI summary
A shift register includes stages to generate gate signals in sequence. Each of the stages includes a first pull up drive control section, a pull up drive section and a pull down drive section. The first pull up drive control section outputs a control signal based on the gate signal of an adjacent stage. The pull up drive section receives a first clock signal and outputs the first clock signal as the gate signal to a corresponding gate line in response to the control signal. The pull down drive section inactivates the corresponding gate line in response to a second clock signal.