In-Cell Display Touch Driving Voltage RMS Equalization
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Solution Overview
Problem
In-cell type display devices experience block dim due to a luminance difference between driving and receiving electrodes caused by a disparity in the root mean square values of voltages supplied during the touch sensing period, leading to image-quality defects.
Innovation Solution
Adjusting the pulse widths of the driving voltage supplied to the driving electrode to match the root mean square value of the reference voltage applied to the receiving electrode, ensuring equal root mean square values for both during the touch sensing period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a driving voltage with pulse type is supplied to the driving electrode during touch sensing period, then touch sensing function is enabled, but block dim is caused due to luminance difference between electrodes
Solution Approach 1:
The patent adjusts the root mean square value of the driving voltage supplied to the driving electrode during touch sensing period to match the root mean square value of the reference voltage supplied to the receiving electrode. This parameter adjustment equalizes the luminance output of both electrodes, eliminating block dim while preserving touch sensing functionality. The specific parameter changed is the voltage amplitude or duty cycle of the pulse signal.
2Illumination intensity
If common voltage is supplied to both driving and receiving electrodes during image display period, then image display is achieved, but touch sensing cannot be performed simultaneously
Solution Approach 1:
The patent employs periodic switching between display mode and touch sensing mode. During display period, common voltage is supplied to both electrodes for image rendering. During touch sensing period, the driving electrode receives pulse-type driving voltage while the receiving electrode receives reference voltage. This periodic alternation allows both functions to operate optimally at different time intervals.
Solution Approach 2:
The patent dynamically adjusts the voltage supplied to electrodes based on operational mode. The driving electrode voltage transitions from common voltage during display to pulse-type driving voltage during touch sensing. The system adapts its electrical characteristics in real-time based on the required function, optimizing performance for each mode.
3Adaptability or versatility
If root mean square values of voltages supplied to driving and receiving electrodes are different during touch sensing period, then touch sensing is enabled, but image quality deteriorates due to block dim
Solution Approach 1:
The patent precisely adjusts the root mean square value of the driving voltage to match that of the reference voltage. This involves calculating and setting the appropriate pulse width, amplitude, or duty cycle of the driving voltage pulse signal so that its RMS value equals the RMS value of the reference voltage, thereby achieving luminance equality and eliminating block dim.
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 adjustment reduces block dim by compensating for voltage deviations between electrodes, thereby enhancing image quality by maintaining equal luminance between driving and receiving electrodes.
Implementation Method 1
An in-cell type display device allows a mutual capacitance to be generated between the touch driving area and the touch sensing area. Thus, the in-cell type display device measures the change in a mutual capacitance that occurs in touch to determine whether there is a touch.
Data Source
AI summary
The display device includes a panel comprising driving electrodes and receiving electrodes, and a touch sensing unit comprising a driver supplying a common voltage to the driving electrodes and the receiving electrodes during an image display period, and sequentially supplying a driving voltage to the driving electrodes to determine whether the panel is touched, during a touch sensing period, and a receiver determining whether there is a touch on the panel based on comparison of a sensing signal induced through the receiving electrodes by the driving voltage with a reference voltage applied to the receiving electrodes. The reference voltage is different from an intermediate level of the driving voltage corresponding to an average of a maximum level and a minimum level of the driving voltage. A root mean square value of the reference voltage is substantially equal to a root mean square value of the driving voltage.