Touch Sensor Electrode Sharing and Time-Sharing Drive
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Solution Overview
Problem
Existing touch panel display devices face challenges in achieving high sensitivity detection due to parasitic capacitance effects, which reduce the accuracy and responsiveness of self-detection methods.
Innovation Solution
The implementation of a display device with a pair of intersecting electrodes, where the common electrode for display is also used for touch sensing, and operations are performed in a time-sharing manner between image display and touch detection, utilizing self-detection and mutual detection methods to enhance sensitivity while minimizing parasitic capacitance influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If self-detection method is used to detect objects with high sensitivity, then detection sensitivity is improved, but parasitic capacitance effects increase and reduce detection accuracy
Solution Approach 1:
The touch panel electrodes are segmented into multiple detection electrodes arranged in a matrix pattern, allowing independent detection of touch positions in different regions. This segmentation enables the system to isolate and measure parasitic capacitance effects locally, improving overall detection accuracy by treating different areas as separate measurement units.
Solution Approach 2:
The system changes detection parameters by applying different excitation voltages and frequencies to different electrodes, and by measuring multiple capacitance parameters (self-capacitance and mutual capacitance) to distinguish between actual touch signals and parasitic capacitance effects. This multi-parameter approach enables accurate differentiation between real touch events and noise.
2Device complexity
If common electrode for display is used as touch sensor electrode, then device complexity is reduced, but detection accuracy is affected by parasitic capacitance
Solution Approach 1:
The common electrode serves dual functions as both the display common electrode and the touch detection electrode. This multi-functional design eliminates the need for separate touch electrode layers, reducing device complexity while maintaining effective touch detection capability through sophisticated signal processing that compensates for parasitic effects.
Solution Approach 2:
The system introduces intermediate detection electrodes and control circuits that act as mediators between the common electrode and the touch detection process. These intermediate elements help isolate and measure parasitic capacitance effects, enabling accurate touch detection despite the shared electrode structure.
3Measurement precision
If time sharing operation is used between image display and touch detection, then parasitic capacitance effects are minimized, but detection response time is increased
Solution Approach 1:
The system employs periodic scanning of detection electrodes in a time-division multiplexed manner, where excitation signals are applied sequentially to different electrodes during vertical blanking periods of the display refresh cycle. This periodic action minimizes interference with image display while maintaining accurate touch detection through systematic sampling of all electrode pairs.
Solution Approach 2:
The system performs preliminary charging of detection electrodes and pre-measurement of baseline capacitance values before actual touch detection. This preliminary action establishes reference levels that enable faster processing of actual touch events, reducing the effective response time penalty associated with time-sharing operation.
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 allows for improved detection sensitivity and accuracy, enabling precise two-dimensional touch position detection with reduced parasitic capacitance effects, enhancing the overall performance of touch-sensitive display devices.
Implementation Method 1
a capacitive touch panel is known in which a plurality of electrodes each formed to extend in a single direction are intersected to each other. In this touch panel, the electrodes are connected to a control circuit, and when supplied with an excitation current from the control circuit, they detect an object close thereto.
Implementation Method 2
Existing touch panel display devices face challenges in achieving high sensitivity detection due to parasitic capacitance effects, which reduce the accuracy and responsiveness of self-detection methods.
Data Source
AI summary
According to one embodiment, a display device with a sensor, includes a pair of electrodes for a touch sensor, which are provided to extend to intersect, and a display panel which includes a plurality of display elements arranged in a matrix, a plurality of gate lines extending along display elements of the display elements which are arranged in a row direction, and a plurality of source lines extending along display elements of the display elements which are arranged in a column direction, wherein a common electrode for display provided in the display panel is also used as one of the electrodes for the touch sensor, the electrodes for the touch sensor are driven by the self-detection method, and an image display operation of the display panel and a drive operation of the electrodes for the touch sensor are performing in a time sharing manner.