GOA Circuit Overcurrent Protection via Level-Shift Detection
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Solution Overview
Problem
The Gate Driver on Array (GOA) circuit in Active Matrix Liquid Crystal Displays (AMLCDs) is prone to short circuits due to high voltage differences and foreign matter, leading to potential melting and temperature rises, necessitating an effective over-current protection system to prevent such incidents.
Innovation Solution
An over-current protection system comprising a power management chip, a level-shift chip with an over-current protection module, including a current comparator, AND gate circuit, rising edge pulse delay circuit, voltage comparator, switches, and a capacitor, which detects excessive current and voltage levels to control power supply to the GOA circuit, preventing overheating and melting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If GOA circuit uses high voltage conversion signals with high alignment and intensive arrangement, then driving capability is improved, but short-circuit risk increases leading to temperature rise and melting
Solution Approach 1:
The patent implements over-current protection by detecting current through a sensing resistor before damage occurs. The control circuit monitors the voltage across the sensing resistor and activates protection mechanisms (turning off switching elements) when current exceeds a threshold, preventing short-circuit damage and melting while maintaining high driving capability
Solution Approach 2:
The patent introduces a sensing resistor as an intermediary element to detect current flow in the GOA circuit. This sensing resistor converts current information into voltage signals that can be processed by the control circuit, enabling indirect monitoring and protection without directly interfering with the high-voltage driving signals
2Reliability
If external IC is used for horizontal scan line driving, then over-current protection can be implemented, but welding process complexity and production cost increase
Solution Approach 1:
The patent merges the over-current protection function with the GOA circuit itself by integrating the sensing resistor and control circuit directly into the array substrate. This eliminates the need for separate external ICs and their associated welding processes, reducing production complexity while maintaining protection capability
Solution Approach 2:
The GOA circuit is designed to perform multiple functions: driving the horizontal scan lines and providing over-current protection. The sensing resistor and control circuit serve dual purposes of monitoring current and activating protection mechanisms, making the circuit universal and eliminating the need for dedicated external protection ICs
Data Source
Figure 1
AI summary
An overcurrent protection system and method for a gate driver on array (GOA) circuit. The overcurrent protection system of the GOA circuit comprises: a power management chip (1) and a level shift chip (2). An overcurrent protection module (21) is provided in the level shift chip (2), and the overcurrent protection module (21) comprises: a current comparator (10), an AND gate circuit (20), a rising edge pulse delay circuit (30), a power supply (40), a voltage comparator (50), a first switch (K1), a second switch (K2) and a capacitor (C). The current comparator (10) is used to detect the current (Isense) on a clock signal trace in the GOA circuit, and control the power supply (40) to charge the capacitor (C) when the current (Isense) on the clock signal trace in the GOA circuit is too high. The voltage comparator (50) is used to detect two ends of the capacitor (C), i.e., a first node voltage, and output an overcurrent protection control signal (OCF) to the power management chip (1) when the first node voltage is too high, so as to control the power management chip (1) to stop supplying power to the GOA circuit. Thus, the overcurrent protection of the GOA circuit is achieved, and the screen melting caused by short circuit of the GOA circuit may be avoided.