Touch Sensing Display Device Noise Reduction via Periodic Driving
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Solution Overview
Problem
Touch sensing display devices with embedded touch sensors in the pixel region face challenges in noise characteristics, particularly when displaying moving images, leading to potential issues with window movement and increased production costs due to the need for noise reduction and sensitivity improvement.
Innovation Solution
A touch sensing display device with a timing controller that alternates display and touch driving periods, using a touch controller to output compensation values for charge remover capacitance, voltage, and gain, and a power controller to supply charge remover voltage, which are stored in a lookup table to improve touch noise characteristics by varying capacitance values in the touch driving circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate touch panel is stacked on the display device, then touch sensing function is achieved, but the thickness of the display device increases
Solution Approach 1:
The patent combines the touch sensor and display pixel into a single integrated structure where the touch sensor is embedded within the pixel region. The touch electrode is formed in the same layer as the pixel electrode, eliminating the need for a separate stacked touch panel and reducing overall device thickness while maintaining touch sensing functionality.
Solution Approach 2:
The touch sensor is nested within the pixel structure by embedding the touch electrode inside the pixel region. This nested configuration allows the touch sensing function to be incorporated without adding external layers, thus reducing thickness while preserving both display and touch capabilities.
2Reliability
If a separate touch panel is stacked on the display device, then touch sensing function is achieved, but light transmission efficiency decreases
Solution Approach 1:
By merging the touch sensor and display into a single integrated structure, the patent eliminates multiple stacked layers that would otherwise impede light transmission. The integrated design reduces the number of interfaces and materials light must pass through, thereby improving light transmission efficiency while maintaining touch sensing capability.
3Length of moving object
If touch sensor is embedded in pixel region, then thickness is reduced, but noise characteristics worsen when displaying moving images
Solution Approach 1:
The patent segments the driving period into distinct display driving periods and touch driving periods. During display driving periods, the touch sensor is inactive, and during touch driving periods, display output is suspended. This temporal segmentation prevents interference between display signals and touch sensing signals, reducing noise characteristics when displaying moving images.
Solution Approach 2:
The patent implements periodic alternation between display driving periods and touch driving periods. This periodic action allows the system to switch between display mode and touch sensing mode, preventing simultaneous operation that would cause noise and interference, thereby improving noise characteristics during moving image display.
4Measurement precision
If amplification circuit is used to improve touch sensitivity, then touch sensitivity increases, but sensing signal becomes saturated due to charging voltage
Solution Approach 1:
The patent introduces a charge remover circuit as an intermediary between the amplification circuit and the touch sensor. This charge remover circuit periodically removes accumulated charging voltage from the amplification circuit, preventing signal saturation while allowing the amplification circuit to maintain high touch sensitivity during active sensing periods.
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 solution maintains a constant touch sensing output voltage during both low- and high-grayscale image data, reducing noise and ensuring smooth window movement during moving image driving, thereby enhancing the overall performance of touch sensing display devices.
Implementation Method 1
detect a touch point where a hand or a stylus pen comes into contact and output information corresponding to the touch point or perform calculation when electrical characteristics such as resistance or capacitance change at the touch point
Implementation Method 2
a touch sensing signal is integrated through an amplification circuit to improve touch sensitivity of the display panel and remove noise for touch sensing
Implementation Method 3
a charge remover circuit that removes a charging voltage of the amplification circuit is used together in order to prevent a sensing signal of the amplification circuit from being saturated
Data Source
AI summary
A touch sensing display device and a driving method thereof for improving touch noise characteristics during moving image driving are discussed. The touch sensing display device can include a display panel including touch electrodes and subpixels defined by data lines and gate lines, and a timing controller configured to output an average data value and a touch synchronization signal in which display driving periods and touch driving periods are alternately time-divided, a touch controller configured to output a charge remover capacitance compensation value, a charge remover voltage compensation value, and a gain compensation value according to the average data value. Further, the touch sensing display device can include a power controller configured to output a charge remover voltage according to the charge remover voltage compensation value, and a touch driving circuit configured to sense a touch signal from each touch electrode and output a touch sensing value.