Voltage Supply Unit for Display Panel Shutdown Afterimage Prevention
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Solution Overview
Problem
Large-size, high-resolution TFT-LCD display panels face shutdown afterimages due to incomplete charge release during power-off, as the level shifter's current driving capability is insufficient to maintain high voltage signals at the required levels.
Innovation Solution
A voltage supply unit comprising a control circuit, a capacitor circuit, and a unidirectionally-conductive circuit that controls the flow of current to charge the capacitor and bootstrap the voltage during shutdown, ensuring complete charge release and preventing afterimages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the level shifter uses standard voltage output during shutdown, then power consumption is reduced, but the driving capability becomes insufficient to maintain high voltage signals, causing shutdown afterimages
Solution Approach 1:
The capacitor circuit is pre-charged to a high voltage level (e.g., 20V) before shutdown occurs. During shutdown, this pre-charged capacitor provides the necessary high voltage to the gate driving signal output end, enabling complete charge release from the display panel without requiring the level shifter to maintain high power output.
Solution Approach 2:
The capacitor circuit acts as an intermediary energy storage device between the power supply and the level shifter output. It decouples the power consumption during operation from the power requirements during shutdown, providing supplemental voltage only when needed to prevent afterimages.
2Power
If the level shifter maintains high voltage signals during shutdown, then complete charge release is achieved, but power consumption increases and driving capability requirements are not met
Solution Approach 1:
The capacitor is charged to the required high voltage level before shutdown occurs. This preliminary charging action ensures that when shutdown happens, the capacitor can immediately provide the high voltage needed for complete charge release, without requiring the level shifter to continuously maintain high power output.
Solution Approach 2:
The system dynamically changes the voltage parameter at the gate driving signal output end based on the operational state. During normal operation, the voltage follows the level shifter output. During shutdown, the capacitor maintains the voltage at a high level (e.g., 20V) even when the level shifter reduces its output, thereby preventing afterimages without continuous high power consumption.
3Device complexity
If a simple voltage output method is used, then device complexity is reduced, but the driving capability is insufficient for large-size high-resolution panels
Solution Approach 1:
A capacitor circuit is introduced as an intermediary component between the power supply and the level shifter. This simple passive component provides supplemental voltage during shutdown without requiring complex active circuitry, thereby maintaining low device complexity while significantly improving output driving capability for large-size high-resolution panels.
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 solution effectively increases the driving current and voltage to the display panel during shutdown, preventing afterimages and enhancing the reliability of large-size display panels like 75-inch 8K panels without modifying the original hardware architecture.
Implementation Method 1
a capacitor circuit, and a unidirectionally-conductive circuit. A control end of the control circuit is connected to a first voltage output end, a first input end of the control circuit is connected to a first end of the capacitor circuit
Implementation Method 2
The unidirectionally-conductive circuit is configured to, when a difference between a first level inputted by the first level end and a potential at the first end of the unidirectionally-conductive circuit is greater than or equal to a predetermined on-state voltage, allow a unidirectional current flowing from the first level end to the first end of the unidirectionally-conductive circuit to flow therethrough
Data Source
AI summary
A voltage supply unit includes a control circuit, a capacitor circuit and a unidirectionally-conductive circuit. The control circuit controls an output end of the control circuit to be electrically connected to a first input end or a second input end of the control circuit under the control of a voltage signal from a first voltage output end. The capacitor circuit controls a potential at a first input end. When a difference between a first level and a potential at the first input end is greater than or equal to a predetermined on-state voltage, the unidirectionally-conductive circuit allows a unidirectional current flowing from a first level end to a first end thereof, and when the difference between the first level and the potential at the first input end is smaller than the predetermined on-state voltage, controls the first level end to be electrically disconnected from the first input end.