Capacitive Touch Sensor Common Electrode Integration
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Solution Overview
Problem
Capacitive type touch sensors for liquid crystal displays face challenges in thickness increase due to the need for a conductive film and limited design flexibility, making them unsuitable for mobile devices, and suffer from signal leakage issues due to grounding resistors, leading to decreased detection accuracy.
Innovation Solution
A capacitive touch sensor system with a switch element that alternates between grounding and floating states, using timing control signals to manage the detection signal and prevent leakage, integrated with the display control circuit to enhance detection accuracy and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive film is arranged for the capacitive touch sensor, then the touch sensor can be formed, but the whole thickness of the liquid crystal module increases
Solution Approach 1:
The patent combines the touch sensor drive electrode with the common electrode of the liquid crystal display. The common electrode serves dual purposes: as the common voltage electrode for display and as the drive electrode for the capacitive touch sensor. This merging eliminates the need for a separate conductive film layer, thereby maintaining thin module thickness while preserving touch sensor functionality.
Solution Approach 2:
The common electrode is designed to perform multiple functions simultaneously. It acts as both the common voltage electrode for displaying images and the drive electrode for capacitive touch detection. This multi-functionality reduces the number of separate components needed, avoiding thickness increase while achieving both display and touch sensor objectives.
2Stability of the object's composition
If a grounding resistor is used to prevent floating potential, then the detection signal is stabilized, but signal leakage occurs leading to decreased detection accuracy
Solution Approach 1:
The patent employs a switching element that dynamically connects or disconnects the detection electrode from ground based on operational requirements. During touch detection, the switching element disconnects the detection electrode from ground, preventing signal leakage while maintaining signal stability. This dynamic connection/disconnection resolves the contradiction between signal stabilization and leakage prevention.
Solution Approach 2:
The switching element acts as an intermediary between the detection electrode and ground. It controls the electrical connection state, allowing the detection electrode to be isolated from ground during detection to prevent leakage, while still providing a reference path when needed. This intermediary component enables both signal stability and high detection accuracy.
3Adaptability or versatility
If the conductive film is arranged deep in the liquid crystal display element, then the design flexibility is reduced, but the position is limited
Solution Approach 1:
By merging the touch sensor drive electrode with the common electrode, the patent eliminates the need to position a separate conductive film deep within the display structure. The common electrode is already positioned on the display side, providing natural positioning freedom and design flexibility without requiring additional deep-layer arrangements.
4Device complexity
If a touch sensor is mounted on the liquid crystal display, then the buttons are integrated, but the whole thickness increases
Solution Approach 1:
The patent merges the touch sensor functionality with the existing liquid crystal display structure by making the common electrode serve as the touch sensor drive electrode. This integration eliminates the need for separate touch sensor components and their associated conductive films, achieving component integration without increasing module thickness.
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
The solution allows for accurate object detection with reduced signal leakage, improving detection sensitivity and flexibility, enabling the use of capacitive touch sensors in thinner, more flexible designs suitable for mobile devices.
Implementation Method 1
a dielectric material located between the first drive electrode and the first detection electrode defining a capacitive area
Data Source
AI summary
A capacitive type touch sensor appropriately detecting an object, and a display and an electronic device including such a touch sensor are provided. The display including a drive electrode receiving a drive signal, a detection electrode located adjacent to the drive electrode, and a dielectric material located between the drive electrode and the detection electrode defining a capacitive area. The detection electrode generates an output signal driven by the drive signal, a detection circuit electrically connected to the detection electrode sensing the output signal. A switch element is electrically connected between the detection electrode and a voltage source providing a predefined voltage level and having a first state and a second state. A display control circuit controls a voltage applied between a display common voltage electrode and a pixel electrode to display an image based on an image signal, and the display common voltage electrode serves as the drive electrode.