Touch Panel Electrode Geometry for Noise-Immune Capacitance Detection
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Solution Overview
Problem
In display devices with integrated touch panels, differences in driving electrode widths lead to unequal electrostatic capacitance between driving and detecting electrodes, resulting in reduced noise immunity and detection accuracy.
Innovation Solution
The input device employs a configuration where the widths of detecting electrodes are adjusted to match the overlapping areas with driving electrodes, using expanding portions to equalize capacitance, ensuring consistent electrostatic capacitance across all electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the width of driving electrodes is made different to match pixel electrode arrangements, then display device functionality is improved, but electrostatic capacitance between driving and detecting electrodes becomes unequal, reducing noise immunity and detection accuracy
Solution Approach 1:
The detecting electrode is designed with non-uniform width along its length, with specific portions having different widths. The first detecting electrode has a first width at its first portion and a second width at its second portion, while the second detecting electrode has a third width at its first portion and a fourth width at its second portion. This local variation in electrode dimensions allows compensation for the varying driving electrode widths, ensuring uniform electrostatic capacitance across all detecting electrodes despite the driving electrodes having different widths to accommodate pixel arrangements.
2Adaptability or versatility
If the width of driving electrodes is varied to accommodate different pixel counts, then display configuration flexibility is improved, but electrostatic capacitance uniformity deteriorates, reducing noise immunity
Solution Approach 1:
The detecting electrodes are designed with locally varied widths to compensate for the varying driving electrode widths. The first detecting electrode has different widths at different portions, and the second detecting electrode has different widths at different portions, allowing each detecting electrode to maintain uniform electrostatic capacitance regardless of which driving electrode it pairs with. This ensures consistent noise immunity across all detecting electrodes.
Solution Approach 2:
The physical dimension parameter (width) of the detecting electrodes is changed locally at different portions to compensate for the width variations in driving electrodes. By adjusting the width parameter of the detecting electrodes in specific regions, the electrostatic capacitance remains uniform across all detecting electrodes, thereby maintaining noise immunity while allowing flexible display configurations.
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 maintains noise immunity and detection accuracy by equalizing electrostatic capacitance, preventing variations due to differing driving electrode widths.
Implementation Method 1
a plurality of capacitive elements composed of a pair of electrodes disposed to face each other via a dielectric layer, namely, a driving electrode and a detecting electrode, is provided in plane of the touch panel. When an input action has been performed by bringing such an input tool as a finger of a user or a touch pen into contact with a capacitive element, a capacitance is added to the capacitive element, so that a detected capacitance is changed
Data Source
AI summary
A noise immunity of a detected capacitance is prevented or inhibited from lowering on a driving electrode different in width from the other driving electrodes, provided in an input device. A touch panel serving as an input device has a plurality of driving electrodes extending in an X-axis direction and arranged in a Y-axis direction intersecting with the X-axis direction, and a driving electrode arranged outside one side of an arrangement of the driving electrodes and extending in the X-axis direction. Further, the touch panel TP1 has a plurality of detecting electrodes extending in the Y-axis direction and arranged in the X-axis direction. The width of the driving electrode is smaller than the widths of the driving electrodes and the detecting electrode includes an expanding portion for expanding the area of the detecting electrode on the side opposite to the plurality of driving electrodes via the driving electrode.