LCD Gate Driver Compensation Circuit for TFT Shutdown Voltage Stability
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Solution Overview
Problem
In liquid crystal display devices, the shutdown voltage for TFTs is affected by coupling effects, leading to voltage fluctuations and incomplete shutdown, resulting in abnormal displays due to increased resistance in wire-on-array paths and signal interference between data lines and VCOM signals.
Innovation Solution
A compensation circuit comprising a first capacitor, a first resistor, a second resistor, and an operational amplifier is used to stabilize the shutdown voltage by determining the resistance ratio between the resistors based on experiment results, ensuring the shutdown voltage is maintained effectively, independent of signal paths, thereby eliminating coupling effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shutdown voltage is delivered through the wire-on-array path, then the TFT can be shut down, but the resistance in the wire-on-array path causes voltage fluctuations and incomplete shutdown
Solution Approach 1:
The patent introduces an independent voltage delivery path as an intermediary to deliver shutdown voltage directly to the gate driver, bypassing the high-resistance wire-on-array path. This mediator path includes a capacitor connected to the gate driver's power supply terminal, providing a stable voltage source that is not affected by the resistance in the original path, thereby eliminating voltage fluctuations and ensuring complete TFT shutdown.
2Reliability
If data lines and VCOM signals are transmitted through the same path, then signal interference occurs due to coupling effects, but separating paths increases device complexity
Solution Approach 1:
The patent segments the signal transmission paths by providing separate connection routes for data lines and VCOM signals. The data lines are connected through one path while the VCOM signal is delivered through an independent path to the compensation circuit. This segmentation eliminates coupling effects and signal interference between the two signal types, ensuring signal integrity without requiring complete structural redesign.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compensation circuit stabilizes the shutdown voltage, preventing incomplete TFT shutdown and abnormal displays by reversing the coupling effect, ensuring accurate voltage delivery and maintaining display quality.
Implementation Method 1
a first terminal of the second resistor being connected to the output terminal of the operational amplifier; the positive input terminal of the operational amplifier receiving an externally supplied shutdown voltage for the gate driver
Implementation Method 2
a first capacitor, a first resistor, a second resistor and an operational amplifier; wherein the first terminal of the first capacitor being connected to the receiving terminal of the gate driver of the liquid crystal display device for receiving shutdown voltage to shutdown TFT
Data Source
AI summary
The present invention provides a liquid crystal display device, compensation circuit and TFT voltage shutdown method. The compensation circuit includes first capacitor, first resistor, second resistor and operational amplifier; wherein first terminal of first capacitor connected to receiving terminal of gate driver of LCD for receiving shutdown voltage to shutdown TFT; first terminal of first resistor connected to second terminal of first capacitor; first terminal of second resistor connected to second terminal of first resistor and second terminal of second resistor connected to output terminal of operational amplifier; positive input terminal of operational amplifier receiving an externally supplied shutdown voltage for gate driver, and negative input terminal of operational amplifier connected to second terminal of first resistor; wherein connection between first capacitor and receiving terminal of gate drive independent from connection between output terminal of operational amplifier and receiving terminal of gate driver.