Duplex Fingerprint Sensor Array Eliminates Bezel

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Solution Overview

Problem

Existing fingerprint sensors face challenges with high material costs, complex manufacturing processes, reduced product yield, and design constraints due to the use of a bezel as a strong outer AC signal source, which also results in slow frame rates and insufficient sensitivity.

Innovation Solution

A fingerprint sensing device with a substrate and an array of sensor cells that operate in duplex mode, transmitting and receiving orthogonal signals simultaneously, eliminating the need for a bezel and enhancing sensitivity and frame rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a bezel is used as a strong outer AC signal source, then the signal strength is improved, but the material cost increases and manufacturing complexity increases

Engineering Contradiction:

Improvesignal strengthVSAvoidmanufacturing complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent removes the bezel structure entirely and extracts the signal transmission function to individual sensor cells. Each sensor cell transmits AC signals independently through the finger to adjacent sensor cells, eliminating the need for a separate bezel component while maintaining signal transmission capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Sensor cells serve themselves by transmitting signals through the finger to neighboring cells. The system uses the finger itself as the transmission medium, and each sensor cell both transmits and receives signals, eliminating the need for external signal generation components.

Inventive Principle:

Principle #25Self-service

2Power

If a bezel is used as a strong outer AC signal source, then the signal strength is improved, but the product yield decreases

Engineering Contradiction:

Improvesignal strengthVSAvoidproduct yield

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

By removing the bezel structure, the patent eliminates an additional manufacturing step and component integration process. The simplified structure without the bezel reduces manufacturing complexity and improves product yield while maintaining signal transmission through the finger-based capacitive coupling mechanism.

Inventive Principle:

Principle #2Taking out (Extraction)

3Device complexity

If sensor cells switch between transmit and receive modes, then the device complexity is reduced, but the frame rate decreases

Engineering Contradiction:

Improvedevice complexityVSAvoidframe rate

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The patent combines transmit and receive functions within each sensor cell, creating a duplex mode where each cell simultaneously transmits signals through the finger and receives signals from neighboring cells. This merging of functions eliminates the need for mode switching while maintaining full sensing coverage across all cells.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

All sensor cells operate continuously in both transmit and receive modes simultaneously, eliminating idle periods associated with mode switching. This continuous operation of all cells in parallel enables high frame rates while capturing complete fingerprint data.

Inventive Principle:

Principle #20Continuity of useful action

4Device complexity

If only some cells transmit signals, then the device complexity is reduced, but the transmitting power is insufficient

Engineering Contradiction:

Improvedevice complexityVSAvoidtransmitting power

Core Design Contradiction:

Device complexityVSPower

Solution Approach 1:

The patent merges the signal transmission capability into all sensor cells rather than limiting it to a separate bezel or selected cells. Each sensor cell transmits AC signals through the finger to adjacent cells, providing distributed transmitting power across the entire sensor array while maintaining simple cell-level operation.

Inventive Principle:

Principle #5Merging (Combining)

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 approach provides higher transmitting power, faster frame rates, and improved noise immunity, making it more suitable for human-machine interfacing applications while reducing material costs and design complexity.

Implementation Method 1

Each sensor cell either transmits or receives signals... each sensor cell transmits one group-identifiable signal and receives seven group-identifiable signals... Each sensor cell in a group transmits the group-identifiable signal of the respective group. At the same time, each sensor cell receives group-identifiable signals from other sensor cells.

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS10121045B2Fingerprint sensor array having duplex sensor cells

Publication Date: 2018.11.06 SILEAD

AI summary

A fingerprint sensing device comprises a substrate and an array of sensor cells formed over the substrate. The sensor cells are divided into multiple groups. Each group is associated with a group-identifiable signal. The sensor cells in each group are configured to transmit the group-identifiable signal of the respective group and are further configured to simultaneously receive the group-identifiable signals transmitted by the sensor cells in other groups. The group-identifiable signals are orthogonal with respect to each other.