Capacitive Touch Panel with Floating Z-Electrode for Pen Detection
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Solution Overview
Problem
Capacitive touch panels struggle to accurately distinguish between finger and insulating pen inputs, leading to poor detection accuracy and requiring dedicated pens, which are costly and complex.
Innovation Solution
A capacitive touch panel with overlapping X-electrodes, Y-electrodes, and a floating Z-electrode that changes capacitance values when touched, allowing for differentiation between finger and pen inputs based on signal polarity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a touch panel of capacitance type is used to detect touch input, then the structure is simpler and costs less compared to resistance film type, but it cannot accurately detect touch with insulating pens (resin stylus)
Solution Approach 1:
The electrode structure is segmented into three distinct layers: X-electrodes in the first substrate, Y-electrodes in the second substrate, and Z-electrodes in the third substrate. This segmentation allows each electrode layer to serve specific detection functions, enabling the system to distinguish between different touch types (finger vs. insulating pen) while maintaining a relatively simple overall structure.
Solution Approach 2:
The Z-electrodes act as an intermediary layer between the X-electrodes and Y-electrodes. When an insulating pen touches the panel, the Z-electrodes detect the capacitance change caused by the pen's proximity, serving as a mediator that enables detection of insulating objects without requiring the touch object to be conductive.
2Adaptability or versatility
If a combination of touch panel and transparent digitizer is used to enable both finger and pen input, then touch detection capability is improved, but the device becomes more complex and costly
Solution Approach 1:
The patent merges the touch panel and digitizer functions into a single integrated structure. The three-electrode system (X, Y, and Z electrodes) combines the capabilities of detecting both conductive (finger) and insulating (pen) touches within one device, eliminating the need for separate touch panel and digitizer components.
Solution Approach 2:
The three-electrode capacitive touch panel achieves multi-functionality by detecting multiple touch types using the same electrode structure. The system can distinguish between finger touches (detected through capacitance coupling between X and Y electrodes) and insulating pen touches (detected through capacitance coupling involving Z electrodes), making the device universal for different input methods.
3Measurement precision
If dedicated pens are required for insulating pen input, then input precision is maintained, but cost increases and operation becomes less convenient
Solution Approach 1:
The patent changes the detection parameters by introducing Z-electrodes that measure capacitance coupling in a different configuration. Instead of requiring specific pen properties (dedicated pens), the system detects touch by measuring capacitance changes caused by the proximity of any insulating object to the Z-electrodes, maintaining detection accuracy while allowing use of ordinary pens.
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
Enhances detection accuracy by distinguishing between finger and pen inputs, improving touched position detection and reducing costs by eliminating the need for dedicated pens.
Implementation Method 1
the Z-electrode is in an electrically floating state, and configured to be overlapped with the adjacent X-electrode and Y-electrode in a planar view. When the touch panel surface is touched, the Z-electrode is elastically deformed, so that each interval between the X-electrode and the Z-electrode, and between the Y-electrode and the Z-electrode changes. Accordingly, the added capacitance value between the X-electrode and Y-electrode via the Z-electrode changes.
Implementation Method 2
When the touch panel surface is touched, the Z-electrode is elastically deformed
Data Source
AI summary
A touch panel of capacitance type includes plural X-electrodes, plural Y-electrodes, and a Z-electrode. Each of the X-electrode and the Y-electrode is formed to have pad portions and thin line portions alternately arranged in an extending direction. The pad portion of the X-electrode and the pad portion of the Y-electrode are arranged without being overlapped in a planar view. The Z-electrode is electrically in a floating state, and formed to be overlapped with both the adjacent X-electrode and the Y-electrode in a planar view. The touched position is calculated based on a local minimal point as an intersection with the interelectrode capacitance value that is equal to or smaller than each of the interelectrode capacitance values of four peripheral intersections among those at the intersections between the plural X-electrodes and the plural Y-electrodes.