Pixel Gate Voltage Switching for Low-Frequency Display Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display devices using low-temperature polycrystalline silicon transistors experience increased leakage currents at higher temperatures or lower driving frequencies, leading to display defects such as vertical crosstalk and flicker due to shifting threshold voltages.
Innovation Solution
The display device employs a variable refresh rate method with distinct high gate voltage levels in address and self-scan periods to manage leakage currents, using transistors with different gate-off voltages in each period to maintain optimal transistor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the driving frequency of the display device is decreased, then power consumption is reduced, but leakage current increases causing display defects
Solution Approach 1:
The gate-off voltage is dynamically adjusted based on the driving frequency. During self-scan periods at lower driving frequencies, the gate-off voltage is increased to a higher level (second high gate voltage) to compensate for increased leakage current, while during address scan periods the standard high gate voltage is used. This dynamic adjustment allows the display to maintain low power consumption at reduced frequencies while preventing display defects.
Solution Approach 2:
The patent changes the voltage parameter of the gate signal specifically during self-scan periods by applying a second high gate voltage with a higher absolute level than the standard high gate voltage. This parameter change targets the leakage current issue that becomes prominent at lower driving frequencies, allowing the system to operate efficiently without sacrificing display quality.
2Temperature
If the temperature of the display device increases, then display performance is improved, but leakage current increases causing vertical crosstalk and flicker
Solution Approach 1:
The patent adjusts the gate-off voltage parameter in response to temperature-induced leakage current increases. By raising the gate-off voltage to a second high gate voltage level during self-scan periods, the system compensates for the increased leakage current that occurs at higher temperatures, thereby maintaining display quality without requiring temperature reduction.
Solution Approach 2:
The patent applies preliminary anti-action by proactively increasing the gate-off voltage during self-scan periods before leakage current problems manifest. This preventive measure counteracts the tendency of leakage current to increase with temperature, preventing vertical crosstalk and flicker before they occur.
3Device complexity
If a single high gate voltage level is used in all periods, then device complexity is reduced, but leakage current cannot be effectively controlled during self-scan periods
Solution Approach 1:
The gate voltage control is segmented into different levels based on the scan period type. During address scan periods, the standard high gate voltage is applied, while during self-scan periods, a second high gate voltage with higher absolute level is applied. This segmentation allows effective leakage current control during self-scan periods without significantly increasing overall device complexity, as the distinction is based on timing rather than additional hardware.
Data Source
AI summary
A display device includes a display panel including a pixel, a gate driver which provides a plurality of gate signals to the pixel, a data driver which provides a data voltage to the pixel in an address scan period and does not provide the data voltage to the pixel in a self-scan period, and a power management circuit which provides high gate voltages of the gate signals to the gate driver. A level of a high gate voltage which is one of the high gate voltages in the self-scan period may be different from a level of the high gate voltage in the address scan period.