OLED Data Driver Noise Suppression via Preliminary Charging
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Solution Overview
Problem
Active matrix OLED display devices experience rapid voltage changes in data lines due to parasitic capacitance, leading to image quality degradation and touch detection errors in touch screens caused by coupling noise between the power supply wire and touch sensor wires.
Innovation Solution
A display device and method that involve a demux unit and data driver to apply previous data signals to data lines at predetermined time intervals, ensuring the voltage remains consistent before a gate-on voltage is applied, thereby suppressing rapid voltage changes and reducing coupling noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data signals are applied to data lines without controlled slew rate, then operation speed is improved, but image quality deteriorates due to rapid voltage changes causing coupling noise
Solution Approach 1:
The patent applies preliminary action by pre-charging data lines with previous frame's data signals before new data signals are applied. This preliminary charging reduces the voltage change magnitude when new data arrives, thereby suppressing rapid voltage transitions and the resulting coupling noise to touch sensor wires, while still maintaining efficient operation speed.
2Object-affected harmful factors
If data signals are applied with controlled slew rate, then coupling noise is reduced, but productivity decreases due to slower voltage transitions
Solution Approach 1:
The patent performs preliminary charging of data lines using stored previous frame data signals before the actual data signal transition. This preliminary action reduces the magnitude of voltage change required, enabling faster transitions without generating excessive coupling noise, thus maintaining productivity while reducing harmful effects.
Solution Approach 2:
The patent implements periodic pre-charging of data lines at the beginning of each frame period. This periodic action ensures that data lines are consistently prepared with appropriate voltage levels before new data arrives, enabling rapid yet controlled transitions that maintain both noise reduction and operational efficiency.
3Speed
If power supply voltage changes rapidly due to parasitic capacitance, then response time is improved, but reliability deteriorates due to harmful influence on image quality
Solution Approach 1:
The patent applies preliminary action by pre-charging data lines with previous frame's data signals before new data signals are applied. This preliminary charging reduces the voltage change magnitude when new data arrives, thereby suppressing rapid voltage transitions and the resulting coupling noise to touch sensor wires, while still maintaining efficient operation speed.
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
This approach prevents rapid voltage changes in data lines, maintaining image quality and reducing touch detection errors by minimizing coupling noise between touch sensor and power supply wires.
Implementation Method 1
as a result of parasitic capacitance between the data line and power supply wire, the power supply voltage may be then be rapidly changed
Implementation Method 2
coupling noise occurs between a wire of the touch sensor and the power supply wire
Data Source
AI summary
A display device is provided including a display unit including a plurality of color pixels; a scan driver that sequentially applies a gate-on voltage scan signal to a plurality of scan lines that are connected to the color pixels; a demux unit that is connected to a plurality of color data lines that are connected to the color pixels, and that sequentially selects the plurality color data lines at a predetermined time interval; and a data driver that applies a data signal to each of the plurality of color data lines that are sequentially selected in the demux unit, and that applies a previous data signal to at least one of the plurality of color data lines during the predetermined time interval, wherein the previous data signal has a same voltage as a voltage applied to one of the plurality of color data lines before the predetermined time interval.