Voltage Control Circuit for Display Panel Residual Charge Discharge
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Solution Overview
Problem
Existing display panels face issues with incomplete discharge of residual charges during shutdown, leading to phenomena like splash screens and afterimages due to insufficient voltage drop in gate-on voltage (VGH) when powered off.
Innovation Solution
A voltage control circuit with a sampling sub-circuit and control sub-circuit that detects potential differences and amplifies or superimposes input voltage with a bootstrap voltage to ensure complete discharge of pixels by fully turning on switching transistors during shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power supply is cut off during shutdown, then energy consumption is reduced, but residual charges cannot be discharged completely causing display abnormalities
Solution Approach 1:
Before completely cutting off the power supply, the patent first activates a discharge circuit that uses residual energy to turn on all switching transistors in the display panel, ensuring complete discharge of pixel charges. This preliminary discharge action prevents display abnormalities while the power is being cut off, resolving the contradiction between energy reduction and discharge completeness.
2Ease of operation
If gate-on voltage (VGH) is pulled up during shutdown, then switching transistors are turned on for discharge, but VGH drops to ground potential making it difficult to discharge residual charges cleanly
Solution Approach 1:
The patent introduces a discharge control circuit as an intermediary that manages the VGH voltage during shutdown. This circuit ensures VGH remains at an appropriate level long enough to fully turn on switching transistors and discharge residual charges, preventing VGH from dropping to ground potential too early. This mediator resolves the contradiction between ease of transistor switching and discharge cleanliness.
3Speed
If power is cut off immediately, then shutdown speed is improved, but screen abnormalities like splash screens and afterimages occur due to insufficient discharge
Solution Approach 1:
The patent implements a preliminary discharge phase before complete power shutdown. During this phase, the discharge circuit is activated to ensure all pixel charges are released, preventing display abnormalities. Only after this discharge is complete does the power supply fully cut off, maintaining fast shutdown speed while eliminating harmful display effects.
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 prevents residual charge issues, improving display quality by ensuring complete discharge and avoiding undesirable phenomena like screen scans and afterimages during shutdown.
Implementation Method 1
the sampling sub-circuit is configured to detect a potential difference between an output voltage and an input voltage, obtain a first voltage
Implementation Method 2
the amplification sub-circuit is configured to amplify the first voltage to obtain the second voltage
Implementation Method 3
the comparison sub-circuit is configured to compare the magnitude of the second voltage with the preset second voltage threshold
Implementation Method 4
The energy storage sub-circuit is configured to step down the input voltage to generate a bootstrap voltage
Implementation Method 5
If the first voltage is greater than or equal to the preset first voltage threshold, the input voltage and a preset bootstrap voltage are superimposed and then outputted as the output voltage
Data Source
AI summary
A voltage control circuit comprises a sampling sub-circuit and a control sub-circuit. The sampling sub-circuit is configured to detect a potential difference between an output voltage and an input voltage to obtain a first voltage and output the first voltage to the control sub-circuit. The control sub-circuit is configured to compare a magnitude of the first voltage with a first voltage threshold, if the first voltage is less than the first voltage threshold, output the input voltage as the output voltage, and, if the first voltage is greater than or equal to the first voltage threshold, superimpose and output the input voltage and a bootstrap voltage as the output voltage.