Fingerprint Detection Electrode Placement on Transparent Substrate
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Solution Overview
Problem
Existing fingerprint detection devices in electronic apparatuses face limitations due to the arrangement of detection electrodes and drive circuits, which restrict the use of transparent substrates for both fingerprint detection and display functions, leading to reduced detection sensitivity and increased parasitic capacitance.
Innovation Solution
A fingerprint detection device is designed with detection electrodes on one surface of a substrate and the drive circuit on the opposite surface, allowing for efficient electrostatic capacitance-based fingerprint detection without conductive wires on the detection surface, thereby reducing parasitic capacitance and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If detection electrodes and drive circuits are provided on the same surface of the substrate, then device complexity is reduced, but parasitic capacitance increases and detection sensitivity deteriorates
Solution Approach 1:
The patent applies dimensionality change by moving the drive circuit from the same surface as the detection electrode to the opposite surface of the substrate. This spatial separation in the third dimension (depth/thickness of substrate) reduces parasitic capacitance between the drive circuit and detection electrode while maintaining integrated device structure.
2Ease of manufacture
If detection electrodes are provided above switching elements, then manufacturing is simplified, but the transparent substrate surface cannot be used as detection surface
Solution Approach 1:
The patent inverts the conventional arrangement by placing detection electrodes on the opposite surface to the switching elements rather than above them. This allows the transparent substrate surface to serve as the detection surface while maintaining electrical connection through the substrate, enabling both simplified manufacturing and versatile surface utilization.
3Device complexity
If drive circuit is integrated on the same surface as detection electrode, then device complexity is reduced, but detection errors increase due to parasitic capacitance
Solution Approach 1:
The patent resolves the contradiction between circuit integration and detection accuracy by utilizing the third dimension (substrate thickness) to separate the drive circuit on the opposite surface from the detection electrode. This maintains integrated device architecture while minimizing parasitic capacitance interference that causes detection errors.
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 improved fingerprint detection sensitivity and reduced detection errors by minimizing parasitic capacitance and allowing for a more flexible arrangement of components, facilitating closer placement of the detection surface to the outer casing while maintaining a transparent display surface.
Implementation Method 1
a detection electrode provided on the second surface side of the substrate and configured to detect unevenness of a finger in contact or in proximity on the basis of an electrostatic capacitance change
Data Source
AI summary
A fingerprint detection device includes: a substrate having a first surface and a second surface on an opposite side of the first surface, the first surface serving as a detection surface configured to detect unevenness of an object in contact or in proximity; a detection electrode provided on the second surface side of the substrate and configured to detect unevenness of a finger in contact or in proximity on the basis of an electrostatic capacitance change; and a drive circuit provided on the second surface side of the substrate and configured to supply a drive signal to the detection electrode.