Capacitive Position Sensor Substrate Routing
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Solution Overview
Problem
Capacitive position detecting devices face challenges in accurately detecting the position of a position indicator due to noise interference from display devices and the need for larger substrates to accommodate connecting lines, which affects convenience and design properties.
Innovation Solution
The device features a substrate with electrode conductors on one surface and connecting lines on the opposite surface, using through-holes to connect the lines to the conductors, allowing the connecting lines to be electrostatically shielded and positioned close to each other to enhance noise cancellation and reduce substrate size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If connecting lines are routed along the periphery of the substrate to concentrate electrode conductors, then the substrate size increases, but the convenience and design properties deteriorate
Solution Approach 1:
The connecting lines are moved from the periphery routing (2D surface routing) to the back surface of the substrate (utilizing the third dimension/depth), allowing them to connect to through-holes without increasing substrate area. This dimensional transition resolves the contradiction by enabling compact layout while maintaining connection functionality.
Solution Approach 2:
The connecting lines are positioned within the area occupied by the electrode conductors on the back surface, creating a nested arrangement where connection paths are embedded within the sensor structure rather than extending externally. This nesting eliminates the need for peripheral routing and reduces overall substrate footprint.
2Area of stationary object
If connecting lines are disposed on the back surface of the substrate, then substrate size is reduced, but noise interference from display devices increases
Solution Approach 1:
Through-holes are introduced as intermediary structures that penetrate the substrate, allowing connecting lines on the back surface to establish electrical connection with electrode conductors on the front surface. These through-holes serve as the mediating interface that enables back-surface routing while maintaining signal integrity and reducing noise susceptibility.
Solution Approach 2:
By transitioning connecting lines to the back surface (utilizing the third dimension), the patent creates spatial separation between the signal detection area (front surface electrode conductors) and the connection paths (back surface connecting lines). This dimensional separation reduces electromagnetic interference and noise coupling while maintaining compact substrate size.
3Area of stationary object
If connecting lines are positioned close to each other, then substrate size is reduced, but noise cancellation effectiveness may be compromised
Solution Approach 1:
Positioning connecting lines close together on the back surface (utilizing vertical space rather than horizontal spread) maintains compact substrate size while the through-hole connection structure preserves the electrical integrity and differential signaling capability needed for effective noise cancellation.
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 enables accurate detection of the position indicator while minimizing noise interference and reducing the substrate size, thereby improving convenience and design properties.
Implementation Method 1
the connecting lines are electrostatically shielded by the first electrode conductors 12Y1 to 12Ym, and reception of a transmitted signal from the indicator 40 by the connecting lines is prevented or alleviated
Implementation Method 2
Each of the connecting lines has one end connected to a respective one of the plurality of electrode conductors disposed on the first surface by a through-hole or a via
Implementation Method 3
a signal processing circuit including a differential amplifier circuit configured to calculate a difference between at least two electrode conductors selected from the plurality of electrode conductors. The signal processing circuit detects the position indicated by the indicator from an output of the differential amplifier circuit
Data Source
AI summary
The invention allows size reduction of a sensor of a position detecting device of a capacitive system, which detects a position indicated by an indicator. The sensor has plural electrode conductors that are disposed adjacent to each other and are configured to receive a signal from the indicator on a first surface of a substrate having the first surface and a second surface opposed to each other. The position detecting device includes a signal processing circuit including a differential amplifier circuit that calculates a difference between signals from at least two of the plural electrode conductors. Plural connecting lines are formed on the second surface of the substrate. The plural connecting lines each have one end connected to one of the plural electrode conductors disposed on the first surface by a through-hole or a via formed through the substrate, and the other end connected to a line-concentrated part.