LTPS Display Driver Segmentation for Low-Frequency Leakage
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Solution Overview
Problem
Organic light emitting display devices experience leakage current in low-temperature polycrystalline silicon (LTPS) transistors when driven at low frequencies, leading to deteriorated display quality.
Innovation Solution
A display device is designed to operate in both normal and low-frequency modes, utilizing a scan driver that outputs scan signals with reversed phases for P-type and N-type scan lines, and a data driver that adjusts its operation based on a power control signal to reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the display device operates at low frequency, then power consumption is reduced, but leakage current increases in LTPS transistors
Solution Approach 1:
The scan driver is divided into first and second scan drivers that operate at different frequencies. The first scan driver operates at normal frequency while the second scan driver operates at low frequency, allowing the display to function at low frequency without causing leakage current in all transistors simultaneously.
Solution Approach 2:
The display device uses periodic scanning with different frequencies for different scan line groups. During low frequency operation, the first scan driver periodically scans first scan lines at normal frequency while the second scan driver periodically scans second scan lines at low frequency, maintaining display functionality while reducing overall power consumption.
2Use of energy by moving object
If the second driving voltage is lowered, then power consumption is reduced, but leakage current occurs in LTPS transistors
Solution Approach 1:
Different driving voltages are applied to different groups of scan lines. First scan lines receive first driving voltages while second scan lines receive second driving voltages, allowing localized optimization where some regions can operate at lower voltages for reduced power consumption while others maintain higher voltages to avoid leakage current.
Solution Approach 2:
The display panel is segmented into different scanning regions with independent voltage control. The first scan lines and second scan lines are controlled by separate scan drivers that can apply different driving voltages, enabling selective power reduction without affecting the entire display uniformly.
3Speed
If LTPS transistors are used in the circuit part, then fast response speed is achieved, but leakage current occurs at low frequency
Solution Approach 1:
The pixel circuit transistors are divided into different groups based on their function and timing requirements. Some transistors are optimized for fast switching while others are optimized for low leakage, allowing the circuit to achieve both fast response speed and low leakage current through differentiated transistor design and placement.
Solution Approach 2:
Different transistor parameters are optimized for different functional requirements within the pixel circuit. Transistors requiring fast response are designed with parameters for rapid switching, while transistors in low-frequency operation paths are designed with parameters minimizing leakage current, achieving both performance goals through parameter differentiation.
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 reduces power consumption and maintains display quality by enabling the display device to operate efficiently at low frequencies, minimizing leakage current and its impact on image quality.
Implementation Method 1
An organic light emitting display device may display an image by using an organic light emitting diode which generates light by recombination of electrons and holes
Data Source
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AI summary
A display device including: a display panel including a pixel connected to a first scan line, second scan line, and data line, the pixel including: a first switch connected to the first scan line; a second switch connected to the second scan line; and a light emitting element; a low-frequency driving controller to output a power control signal having a first level in a first mode and a second power control signal having a second level in a second mode; a scan driver including first and second scan drivers to drive the first and second scan lines, wherein one of the first and second scan drivers operates in the second mode; and a data driver to operate in the second mode in response to the power control signal having the second level, wherein the data driver operates at a frequency lower than a reference frequency in the second mode.