Self-Capacitive Electrodes and Cathode for Touch Pressure Detection
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Solution Overview
Problem
Current touch display technologies in mobile devices face limitations in detection accuracy due to structural modifications and assembly tolerance issues when integrating pressure sensing mechanisms, which affect the precision of touch and pressure detection.
Innovation Solution
A touch display device and driving method utilizing self-capacitive electrodes and an electroluminescent display panel, where capacitive structures are formed between the electrodes and a cathode, allowing for simultaneous touch and pressure detection by applying specific detection signals during different time periods to determine touch position and pressure with enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an extra mechanism is added at the backlight portion or middle frame for pressure sensing, then pressure sensing function is achieved, but structural complexity increases and assembly tolerance becomes larger
Solution Approach 1:
The self-capacitive electrodes are designed to serve dual purposes: displaying images and detecting touch/pressure. The electroluminescent display panel's cathode and the liquid crystal display panel's self-capacitive electrodes both function as sensing elements, eliminating the need for separate pressure sensing mechanisms.
Solution Approach 2:
The pressure sensing function is merged with the existing display structure by utilizing the cathode of the electroluminescent display panel and the self-capacitive electrodes of the liquid crystal display panel as sensing elements, rather than adding a separate sensing layer or mechanism.
2Adaptability or versatility
If an extra mechanism is added for pressure sensing, then pressure sensing function is achieved, but detection accuracy is limited due to assembly tolerance
Solution Approach 1:
The mechanical pressure sensing mechanism is replaced with an electrical field-based capacitive sensing system. By measuring changes in capacitance values of the self-capacitive electrodes and cathode, the system achieves high-precision pressure detection without mechanical contact or assembly tolerance issues.
Solution Approach 2:
The system detects pressure by measuring changes in capacitance values caused by variations in distance between the self-capacitive electrodes and the cathode. This electrical parameter change provides high sensitivity and precision for pressure detection.
3Adaptability or versatility
If separate touch and pressure detection mechanisms are used, then both functions are achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The same hardware components (self-capacitive electrodes and cathode) are used for both touch detection and pressure detection. The system achieves multi-functionality by processing different signal characteristics from the same sensing elements during different time periods.
Solution Approach 2:
The system performs touch detection and pressure detection at different time periods using periodic sampling. During the first time period, touch detection signals are applied; during the second time period, pressure detection signals are applied, allowing both functions to be achieved with the same hardware.
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 achieves higher detection accuracy for touch and pressure sensing with minimal modifications to the display device hardware, reducing assembly tolerance limitations and manufacturing costs while maintaining effective touch and pressure detection functionality.
Implementation Method 1
the self-capacitive electrodes in the liquid crystal display panel and a cathode in the electroluminescent display panel constitute capacitive structures; detecting change of a capacitance value of a self capacitance corresponding to each self-capacitive electrode so as to determine a touch position; detecting changes of capacitance values of capacitances formed between the self-capacitive electrodes and the cathode so as to determine a pressure at the touch position
Data Source
AI summary
A touch display device and a driving method are disclosed. The touch display device includes a liquid crystal display panel having a plurality of self-capacitive electrodes and an electroluminescent display panel arranged under the liquid crystal display panel. The self-capacitive electrodes in the liquid crystal display panel and a cathode in the electroluminescent display panel constitute capacitive structures. The driving method includes in a touch detection time period, applying a first touch detection signal to the self-capacitive electrodes and the cathode simultaneously, and detecting change of a capacitance value of a self capacitance corresponding to each self-capacitive electrode so as to determine a touch position; and in a pressure detection time period, applying a second touch detection signal to the self-capacitive electrodes or the cathode, and detecting changes of capacitance values of capacitances formed between the self-capacitive electrodes and the cathode to determine a pressure at the touch position.