Touch Panel Electrode Terminal Selection for Resolution
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Solution Overview
Problem
The electrostatic capacity coupling method for touch panels, as described in JP2006-146895 A, experiences reduced resolution near the center of the detection transparent conductive film due to decreased impedance differences and current ratio differences when a finger is touched, leading to lower detection accuracy.
Innovation Solution
Providing multiple electrode terminals on each side of the detection transparent conductive film, allowing for the selection of two to four terminals to apply an AC signal and detect currents, which increases current differences and range near the center, thereby improving coordinate resolution and reducing detection time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If four electrode terminals are provided at the four corners of the detection transparent conductive film, then the device complexity is reduced and manufacturing cost is lowered, but the detection precision deteriorates in the vicinity of the center due to decreased impedance difference and current ratio difference
Solution Approach 1:
The detection transparent conductive film is divided into multiple detection regions, with electrode terminals strategically positioned at corners and midpoints of sides. This segmentation allows different terminal combinations to be used for different regions, maintaining high detection resolution across the entire film surface while keeping the overall structure manageable and cost-effective.
Solution Approach 2:
Different electrode terminal configurations are applied to different regions of the detection film. For corner regions, four-terminal detection is used, while for central regions, six-terminal or eight-terminal configurations provide enhanced current ratio differences. This local optimization ensures high detection precision where needed without unnecessarily increasing complexity throughout the entire device.
2Measurement precision
If multiple electrode terminals are provided on each side of the detection transparent conductive film, then the detection precision is improved through increased current differences, but the device complexity increases
Solution Approach 1:
The system dynamically selects which electrode terminals to use based on the detected touch region. A touch panel control circuit identifies the touch location and activates the appropriate terminal combination (four terminals for corners, six or eight for central areas). This dynamic adaptation provides high detection precision where needed while keeping the active component count manageable through selective activation.
Solution Approach 2:
The same detection transparent conductive film structure serves multiple functions: it acts as both the display electrode substrate and the touch detection sensor. The electrode terminals serve dual purposes for both display driving and touch detection, eliminating the need for separate sensor electrodes and reducing overall device complexity despite using multiple terminals for enhanced precision.
3Measurement precision
If region division method with current detection is employed, then the detection precision is improved, but the detection time increases
Solution Approach 1:
The detection process is segmented into rapid initial region identification followed by focused coordinate detection. The touch panel control circuit first identifies which detection region contains the touch, then applies current detection only to the relevant terminal combinations for that region. This segmented approach provides high coordinate resolution while minimizing detection time by avoiding full-surface scanning.
Solution Approach 2:
The system performs preliminary region identification before executing detailed coordinate detection. By first determining which detection region is active and selecting the appropriate terminal configuration in advance, the system prepares the optimal detection path, thereby reducing overall detection time while maintaining high precision in the final coordinate calculation.
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 configuration enhances the detection resolution and sampling period of touch panels, achieving a high-resolution touch input at a low cost by optimizing current detection and region division methods.
Implementation Method 1
an electrostatic capacity coupling method is employed... a rear surface ITO in a display panel constituting a liquid crystal display device of in-plane switching (IPS) method can be used as a detection transparent conductive film for detecting an electrostatic capacity generated by a touch of a user's finger
Implementation Method 2
an AC signal is applied through a current detection resistor. A parasitic capacitance and an electrostatic capacity (generated by a touch of a finger) in the detection transparent conductive film are charged and discharged with the AC signal
Data Source
AI summary
A detection resolution is improved in a display device that employs an electrostatic capacity coupling type touch panel provided with a transparent conductive film serving as a detection film. A plurality of electrode terminals (102) is provided such that at least three electrode terminals (102) are aligned in each side of a detection transparent conductive film (101). A touch panel control circuit is provided for selecting one of two to four numbers of electrode terminals from among the plurality of electrode terminals (102) of the detection transparent conductive film (101), applying an AC signal provided from a signal source (105) through a current detection resistor (r) (103), and then detecting a current that flows through each of the selected electrode terminals.