Display Power Supply Switching for Overcurrent-Limited Grayscale Changes
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Solution Overview
Problem
Display devices experience overcurrent issues when switching between high grayscale images, leading to potential damage and inefficiencies.
Innovation Solution
A power supply system with multiple power sources and control mechanisms to manage current flow, including a first power source at ground potential, a second power source for sensing, and a third power source for overcurrent protection, controlled by a timing controller and current sensing unit to adjust voltage levels dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data scaling is applied based on previous frame grayscales, then current frame overcurrent is reduced, but in worst case (black-white switching) overcurrent cannot be prevented
Solution Approach 1:
The patent applies preliminary action by proactively switching to the third power source when overcurrent is detected in the first power line, rather than waiting for damage to occur. The timing controller monitors current levels and preemptively changes the power supply configuration to prevent overcurrent damage, addressing the limitation of reactive data scaling approaches.
Solution Approach 2:
The patent introduces a second power source as an intermediary between the first and third power sources. During normal operation, the second power source is connected to provide stable power. When overcurrent is detected, the system transitions through this intermediary state to the protective third power source configuration, enabling smooth transitions and multiple operational modes.
2Reliability
If multiple power sources are used for overcurrent protection, then overcurrent prevention capability is improved, but power supply system complexity increases
Solution Approach 1:
The timing controller serves multiple functions: it monitors current levels, determines when overcurrent occurs, controls the switching of power sources, and manages the overall power supply configuration. By making the timing controller multi-functional, the patent reduces the need for separate dedicated components for each function, thereby managing complexity while maintaining reliable overcurrent protection.
Solution Approach 2:
The patent combines the monitoring, control, and switching functions into an integrated power supply unit managed by the timing controller. Rather than having separate independent systems for current sensing, decision-making, and power switching, these functions are merged and coordinated through the timing controller's unified control logic.
3Reliability
If data scaling is applied to prevent overcurrent, then device safety is improved, but image quality deteriorates due to luminance reversal
Solution Approach 1:
The patent segments the power supply into three distinct power sources with different voltage levels, allowing selective activation based on operational needs. During normal operation, the first and second power sources provide adequate power for full luminance. When overcurrent is detected, the system transitions to using the third power source, which has lower voltage characteristics that inherently limit current while maintaining sufficient luminance for display functionality.
Data Source
AI summary
A display device according to embodiments of the present inventive concept includes pixels connected to scan lines, data lines, sensing lines, a first power line, and a second power line; and a power supply unit supplying at least one of a first driving power source, a second driving power source, and a third driving power source to the second power line as a second power source, and the power supply unit supplies voltages of the first driving power source and the third driving power source to the second power line during a normal driving period in which the pixels emit light.