Integrated Touch Display Electrodes for Near-and-Far Detection
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Solution Overview
Problem
Existing capacitance-type touch sensors for liquid crystal display devices face challenges in detecting objects at a distance, leading to increased thickness and difficulty in integrating touch sensor circuits with display circuits, especially in mobile device applications where user potential is often unfixed.
Innovation Solution
A capacitance-type touch sensor system that includes drive electrodes and detection electrodes, a detection circuit, and a controller to change the range of electric flux lines, allowing for object detection both when in contact and at a distance by using the common electrode as both a display and sensor drive electrode with a higher voltage signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a capacitance-type touch sensor is attached onto a liquid crystal display device, then information input capability is enabled and space is saved, but the total thickness of the liquid crystal module is increased
Solution Approach 1:
The patent merges the touch sensor function with the liquid crystal display structure by forming the touch sensor electrodes and circuits within the same module. The sensor drive electrode is integrated with the common electrode of the liquid crystal display, and the sensor detection electrode is formed on the observation-side substrate, eliminating the need for separate touch sensor attachments and reducing overall thickness.
Solution Approach 2:
The common electrode of the liquid crystal display serves dual purposes: as a display drive electrode and as a sensor drive electrode for the capacitance-type touch sensor. This multi-functional design allows the same electrode structure to perform both display and touch sensing functions, reducing the number of additional components needed.
2Strength
If a protective layer is added to prevent scratches on the touch sensor, then scratch resistance is improved, but the liquid crystal module thickness is further increased
Solution Approach 1:
The patent uses a thin film protective layer formed directly on the observation-side substrate where the detection electrode is located. This thin film provides scratch protection while minimizing thickness increase, as it is integrated into the existing substrate structure rather than being added as a separate thick protective component.
3Length of stationary object
If the conductive film for touch sensor is placed between the observation-side substrate and polarizing plate, then thickness is reduced, but the user needs to be securely grounded which limits mobile device application
Solution Approach 1:
The patent configures the sensor detection electrode to detect capacitance changes relative to the user's body potential without requiring the user to be grounded. The sensor drive electrode is driven by an AC signal, and the detection circuit measures capacitance changes between the detection electrode and the user's finger, allowing operation in mobile devices where ground potential is not fixed.
4Reliability
If circuit portions for touch sensor drive and coordinate detection are separately provided from display drive circuit, then touch sensing function is achieved, but overall circuits are hard to integrate
Solution Approach 1:
The patent integrates the touch sensor drive circuit and coordinate detection circuit with the display drive circuit on the same substrate. The sensor drive electrode is driven by signals from the display drive circuit, and the detection electrode connects to the same substrate circuits, allowing both display and touch sensing functions to be implemented with a unified circuit architecture.
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
Enables detection of objects at various distances, improving detection sensitivity and allowing for integration of touch sensor and display circuits on a single board, suitable for mobile device applications.
Implementation Method 1
one or more detection electrodes forming capacitance in cooperation with the respective drive electrodes
Implementation Method 2
a controller controlling to change a range of electric flux lines generated between the drive electrodes and the detection electrodes
Data Source
AI summary
A detection device includes a plurality of drive electrodes, wherein: in a first mode, a first drive electrode block including a first number of the drive electrodes are supplied with a first drive signal; in a second mode, a second drive electrode block including a second number of the drive electrodes are supplied with a second drive signal; and the first number is different from the second number.