Alternating Gate Drivers Prevent Transistor Degradation in LCDs
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Solution Overview
Problem
The degradation of transistor characteristics in gate driving units of liquid crystal displays (LCDs) leads to prolonged discharge times and abnormal voltage output, due to uneven stress voltage distribution and low mobility of amorphous silicon hydrogen (a-Si:H) transistors, resulting in unreliable performance.
Innovation Solution
A driving circuit with a pair of alternately driven gate driving units, where each unit operates during alternating frames to distribute stress voltage more evenly across charging and discharging transistors, preventing continuous stress and improving discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single gate driving unit is used to supply gate signals to gate lines, then the device complexity is reduced, but the transistor characteristics degrade due to uneven stress voltage distribution and continuous stress on charging and discharging transistors
Solution Approach 1:
The gate driving unit is divided into a first gate driving unit and a second gate driving unit, each responsible for different time periods (odd frames and even frames respectively). This segmentation allows the charging and discharging transistors in each unit to experience more uniform stress voltage distribution, preventing continuous stress on the same transistors and thereby maintaining transistor characteristics and reliability.
2Ease of manufacture
If amorphous silicon hydrogen (a-Si:H) transistors are used in gate driving units, then the manufacturing ease is improved, but the discharge time is prolonged due to low mobility of the transistors
Solution Approach 1:
The patent employs dual gate driving units that are dynamically switched between odd and even frames. This dynamic operation allows the system to compensate for the low mobility of a-Si:H transistors by providing alternative discharge paths and reducing the continuous stress on individual transistors, thereby improving the effective discharge time performance while maintaining the manufacturing advantages of a-Si:H technology.
3Productivity
If gate driving units operate continuously without alternation, then the productivity is maintained, but the transistor characteristics degrade leading to abnormal voltage output
Solution Approach 1:
The patent implements periodic action by alternating the operation of the first and second gate driving units between odd frames and even frames. This periodic switching ensures that each unit has time to recover and discharge properly, preventing the accumulation of stress voltage and maintaining stable voltage output while ensuring continuous gate signal supply to the liquid crystal panel.
Data Source
AI summary
A driving circuit of a liquid crystal display includes: a timing controller to output a gate control signal and a data control signal to control driving of a gate driving unit and a data driving unit and to output digital video data; a pair of gate driving units to be alternately driven by using at least one frame as a period to supply gate signals to gate lines of a liquid crystal panel in response to the gate control signal; and a data driving unit to supply pixel signals to data lines of the liquid crystal panel in response to the data control signal. Degradation of characteristics of transistors constituting each gate driver can be prevented.