Position Sensor Electrodes with Inclined Dummy Patterns
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Solution Overview
Problem
Position detecting sensors using the cross-point capacitive system face challenges in achieving uniform light permeability and preventing Moire effects when superposed on display devices, leading to complex position detection calculations and potential image distortion.
Innovation Solution
A position detecting sensor with a grid structure of electrodes and dummy patterns that are line-symmetric and inclined to reduce Moire effects, maintaining cross-points on straight lines to simplify position detection without the need for signal correction processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If dummy patterns are added to achieve uniform light permeability, then light permeability uniformity is improved, but device complexity increases
Solution Approach 1:
The sensor surface is segmented into functional electrode regions and dummy pattern regions. The dummy patterns are separated from the functional electrodes by predetermined spaces, allowing independent optimization of each region's function while maintaining overall uniformity.
Solution Approach 2:
Dummy patterns act as intermediary elements that mediate between the functional electrodes and the underlying display pixels. These dummy patterns fill optical gaps and provide a uniform visual appearance without interfering with the capacitive sensing function.
2Measurement precision
If electrodes are arranged in a grid pattern for cross-point capacitive detection, then position detection capability is improved, but Moire effects occur when superposed on display pixels
Solution Approach 1:
The dummy patterns are arranged with asymmetric spacing relative to the functional electrodes. Specifically, the spacing between dummy patterns and adjacent electrodes is predetermined and non-uniform, which disrupts the regular grid pattern that would otherwise create Moire effects with display pixels.
Solution Approach 2:
The solution addresses the two-dimensional Moire problem by introducing a third dimensional consideration - the vertical spacing and optical layering between the sensor electrode layer and display pixel layer. The dummy patterns create an intermediate optical dimension that prevents direct interference alignment.
3Illumination intensity
If dummy patterns are placed close to electrodes to improve uniformity, then light permeability uniformity is improved, but capacitance measurement accuracy may deteriorate
Solution Approach 1:
Different regions of the sensor have different qualities: functional electrode regions have high electrical conductivity for sensing, while dummy pattern regions have optimized optical properties for uniformity. The predetermined spaces between dummy patterns and electrodes create local zones where each property can be optimized independently without compromise.
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
Ensures uniform light permeability and prevents Moire fringes, allowing for precise position detection without signal correction, enhancing the accuracy and usability of the sensor on display devices.
Implementation Method 1
a change in a capacitive coupling state between a sensor electrode and an indication body is detected, to thereby detect a position indicated by the indication body
Data Source
AI summary
A position detecting sensor includes a grid structure composed of plural electrodes extending in a first direction and plural electrodes extending in a second direction perpendicular to the first direction. The electrodes have light permeability. In a rectangular area defined by four cross-points, where two adjacent electrodes extending in the first direction and two adjacent electrodes extending in the second direction cross each other, a dummy pattern is disposed so as to provide uniform optical characteristics for the sensor. At least some of the electrodes extending in the first direction are shaped to include inclinations relative to the first direction, so as to minimize the Moire effect that may develop between the electrodes and an array of pixels in an overlaid display device. Also, at least some of the electrodes extending in the first direction are shaped to be line-symmetric about a straight line extending in the first direction.