LCD Gate Driver Circuit for RC Delay and Pulse Fall Control
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Solution Overview
Problem
The RC delay along gate lines in liquid crystal display (LCD) devices causes distortion of gate pulses, leading to extended falling times and insufficient charging of liquid crystal capacitors, resulting in non-uniform brightness, contrast ratio issues, image sticking, and flicker, which degrade display quality.
Innovation Solution
A driver circuit and method that includes a gate line, a data line, a feed TFT connected to the gate line, a feed control line, and a feed signal line to supply a feed signal synchronized with the gate pulse, shortening the falling time of the gate pulse and ensuring sufficient charging time for liquid crystal capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If gate lines are made longer to cover larger display areas, then the display area increases, but the RC delay increases causing gate pulse distortion and extended falling times
Solution Approach 1:
A feed TFT is introduced as an intermediary component connected to the gate line. This feed TFT receives a feed signal from a feed signal line and transfers it to the gate line, acting as a mediator to actively manage and control the gate pulse signal characteristics along the gate line, thereby compensating for RC delay effects without changing the gate line physical dimensions.
2Length of stationary object
If gate pulse falling time is extended due to RC delay, then the gate line can cover longer distances, but the liquid crystal capacitor charging becomes insufficient leading to display quality degradation
Solution Approach 1:
A feed signal is applied in advance through the feed TFT to the gate line before the main gate pulse arrives. This preliminary action pre-charges or pre-biases the gate line, preparing it to receive and properly transmit the gate pulse signal without excessive delay or distortion, ensuring consistent charging of liquid crystal capacitors across the entire display area.
3Duration of action of moving object
If the feed TFT is added to shorten gate pulse falling time, then the charging time for liquid crystal capacitors is sufficient, but the device complexity increases
Solution Approach 1:
The feed TFT is designed to serve multiple functions: it acts as a signal amplifier, a timing controller, and a voltage regulator simultaneously. By making the feed TFT multi-functional, the patent reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving sufficient charging time for liquid crystal capacitors.
Data Source
AI summary
A driver circuit for an LCD display includes; a gate line; a data line crossing the gate line; a feed TFT connected to the gate line; a feed control line connected to the feed TFT to switch on the feed TFT; and a feed signal line connected to the feed TFT to supply a feed signal to the gate line.