Display Device Dual Power Voltage Generators Overcurrent Protection
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Solution Overview
Problem
Display devices face challenges in maintaining stability and quality due to electrical characteristic deviations between driving transistors and the occurrence of overcurrent issues, which can lead to burnt phenomena, especially when using external compensation methods and DC-DC converters with ripple voltage.
Innovation Solution
A display device with a pixel unit, a sensing unit, and dual power voltage generators, where a timing controller selectively controls power voltage supply modes, including an overcurrent protection circuit with a current detector and limiter, to manage driving currents and prevent overcurrent, while minimizing ripple voltage impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a DC-DC converter is used to generate voltage for driving pixels, then power conversion efficiency is improved, but ripple voltage is generated which degrades the stability and quality of external compensation method
Solution Approach 1:
The patent divides the power supply function into two separate power voltage generators: one dedicated to driving the pixels and another dedicated to sensing the pixels. This segmentation allows each generator to be optimized for its specific function, with the sensing generator providing stable voltage without ripple for accurate compensation measurements.
Solution Approach 2:
The patent introduces a timing controller as an intermediary that selectively controls the operation of the first and second power voltage generators. The timing controller manages the switching between display mode and sensing mode, ensuring that the sensing operation receives clean power from the second generator while the display operation uses the first generator, thus isolating the ripple effect.
2Measurement precision
If external compensation method is used to correct electrical characteristic deviation, then gray scale accuracy is improved, but the method becomes more sensitive to voltage ripple and less stable
Solution Approach 1:
The patent separates the power supply for sensing operations from the power supply for display operations. By using a dedicated second power voltage generator for sensing, the external compensation method receives stable voltage free from the ripple present in the display power supply, thereby maintaining both high measurement precision and stability.
3Device complexity
If commonly connected power source is used for all pixels, then device complexity is reduced, but overcurrent may occur causing burnt phenomenon when current path is short-circuited
Solution Approach 1:
The patent introduces an overcurrent protection circuit as an intermediary between the power source and the pixels. This circuit includes a current detector and a current limiter that actively monitor and control the current flowing through each pixel, preventing overcurrent conditions while maintaining the simple commonly-connected power source configuration.
Solution Approach 2:
The overcurrent protection circuit implements feedback control by continuously detecting the current through each pixel and adjusting the power supply accordingly. When overcurrent is detected, the circuit activates the current limiter to restrict the current to a safe level, providing active protection against burnt phenomena.
Data Source
AI summary
The present inventive concept provides a display device including a pixel unit which includes pixels, a sensing unit connected to the pixels through sensing lines, a first power voltage generator connected to the pixels through a first power line and generating a first power voltage for driving the pixels, a second power voltage generator connected to the pixels through the first power line and generating a second power voltage for sensing the pixels, and a timing controller selectively controlling operations of the first power voltage generator and the second power voltage generator according to a driving method of the pixel unit, and a method driving the same.