Two-Layer Capacitive Touch Sensor Layout With Reduced Routing
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Solution Overview
Problem
Conventional 3-D capacitive touch sensors require multiple layers with conductive materials, leading to complexity, increased cost, and manufacturing challenges, particularly with the use of Indium Thin Oxide (ITO) on glass cover windows, which complicates the production of 2.5-D shapes and GORILLA glass, resulting in high costs and low yields.
Innovation Solution
A two-layer capacitive touch sensor design where the top layer has capacitive sensors arranged in a ring-shaped pattern with minimal routing and no need for a top guard layer, and the bottom layer has capacitive sensors with electrically conductive material positioned under the top layer, utilizing the display's conductive material as a rear guard, thereby reducing the number of conductive layers and eliminating the need for ITO on the cover window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional 3-D capacitive touch sensors use multiple layers with conductive materials including ITO on glass cover windows, then the sensor provides complete capacitive coverage and guarding, but the manufacturing complexity increases and production yields decrease
Solution Approach 1:
The patent removes the top guard layer and ITO from the cover window, extracting unnecessary conductive elements that complicate manufacturing. The second layer capacitive sensors are positioned to provide guarding functions without requiring a separate top guard layer, simplifying the structure while maintaining capacitive coverage.
Solution Approach 2:
The patent combines the guarding function into the second layer capacitive sensors rather than requiring a separate top guard layer. The electrically conductive material on the second layer serves dual purposes: as capacitive sensors and as guarding elements, reducing the total number of required layers and materials.
2Reliability
If conventional 3-D capacitive touch sensors use multiple layers with conductive materials, then the sensor provides complete capacitive coverage, but the manufacturing cost increases
Solution Approach 1:
The patent eliminates ITO from the cover window and removes the top guard layer, extracting expensive materials and complex manufacturing steps. This reduction in material usage and layer count directly lowers manufacturing costs while maintaining essential capacitive functions.
Solution Approach 2:
The patent replaces expensive ITO materials with alternative conductive materials that are cheaper and easier to manufacture. The simplified structure uses standard conductive materials on flexible substrates rather than requiring costly ITO-coated glass, reducing overall material costs.
3Reliability
If conventional 3-D capacitive touch sensors use multiple layers with conductive materials, then the sensor provides complete capacitive coverage, but the device thickness increases
Solution Approach 1:
The patent merges the top guard layer function into the second layer capacitive sensors, eliminating the need for a separate top guard layer. This consolidation reduces the number of discrete layers and their associated thickness, resulting in a thinner overall sensor structure while maintaining capacitive coverage.
Solution Approach 2:
The patent removes the top guard layer and ITO coating from the cover window, extracting unnecessary thickness-contributing elements. The simplified structure requires fewer material layers, directly reducing the z-axis thickness of the touch sensor assembly.
4Reliability
If conventional 3-D capacitive touch sensors use multiple layers with conductive materials, then the sensor provides complete capacitive coverage, but the routing complexity in the viewable area increases
Solution Approach 1:
The patent removes the top guard layer and its associated routing, extracting complex electrical pathways from the viewable area. By eliminating this layer, the patent reduces the number of electrical connections and routing traces that would otherwise need to be managed in the front portion of the sensor.
Solution Approach 2:
The patent segments the capacitive sensor functions into two distinct layers with specific spatial arrangements. The first layer ring-shaped capacitive sensors handle front-facing detection, while the second layer capacitive sensors provide rear guarding functions, separating detection and guarding functions to simplify routing requirements.
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 design makes the touch sensor more compact, cost-effective, and thinner, with reduced manufacturing issues and improved visual appeal, as it minimizes routing in the viewable area and leverages the display's conductive material for guarding, allowing for the use of non-ITO glass and simpler production processes.
Implementation Method 1
a front surface of the first layer is configured to receive a touch input from a user
Data Source
AI summary
An apparatus including a first layer having a first substrate, first capacitive sensors on the first substrate and first electrical leads on the first substrate; and a second layer having a second substrate, second capacitive sensors on the second substrate and second electrical leads on the second substrate. The first layer is located on top of the second layer. The first capacitive sensors are arranged in a substantially ring-shaped pattern. The second capacitive sensors are arranged in a pattern sized to fit under the first layer within an inside perimeter of the substantially ring-shaped pattern of the first capacitive sensors. The second layer includes electrically conductive material spaced from the second capacitive sensors and the second electrical leads. The electrically conductive material is sized and shaped to be located under the first capacitive sensors and the first electrical leads.