Display Device Residual Charge Suppression via Single Power Supply
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional liquid crystal display devices with IGZO-TFTs face issues with residual charge accumulation, leading to display failures such as burn-in and flicker, which are difficult to address with existing two-slope power supply systems due to high cost and complexity.
Innovation Solution
A single power supply system configuration is implemented, using a single type of scanning line selection voltage and non-selection voltage, with a drive control circuit that alternates clock signal voltages and sets the clear signal to ground during power-off to discharge residual charge effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-slope power supply system is used to discharge residual charge, then display failure caused by residual charge is suppressed, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential function of residual charge discharge from the complex two-slope power supply system and implements it through a simplified single power supply system with specific voltage transition control, removing unnecessary complexity while maintaining the core protective function
Solution Approach 2:
The patent changes the voltage parameters and transition timing of the power supply system, using a single power supply with carefully controlled voltage levels during the off sequence to achieve both discharge functionality and system simplification
2Use of energy by moving object
If IGZO-TFTs with excellent off characteristics are used, then power consumption is reduced, but residual charge accumulation occurs causing display failure
Solution Approach 1:
The patent applies preliminary anti-action by implementing a discharge process during the off sequence that actively removes residual charge before it can accumulate to problematic levels, preventing display failure while maintaining the low power consumption benefits of IGZO-TFTs
Solution Approach 2:
The patent employs periodic action through regular off sequences that include voltage transitions designed to discharge residual charge, creating a cyclic process that continuously prevents charge accumulation while maintaining overall low power consumption
Data Source
AI summary
When supply of power has stopped, voltages of GDM signals are set as follows. A clear signal that contributes to removal of charge at floating nodes (an output control node and a stabilization node) in each unit circuit included in a shift register is set to a voltage of ground, and other signals (a gate start pulse signal, gate clock signals, and a reference voltage) are set to a gate-on voltage. To implement such settings, a single power supply system configuration that uses a voltage of only one channel as a scanning line selection voltage is adopted.