Hover Detection for Fingerprint Imaging

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Solution Overview

Problem

Conventional fingerprint sensor wake-up schemes in electronic devices often rely on mechanical button presses, which are inaccurate and impractical when the sensor is integrated within the active display area, leading to false rejections and increased power consumption.

Innovation Solution

A method using a touch screen sensor to initiate fingerprint capture by placing the device in a hover detect mode, illuminating the sensing region upon detecting a hovering finger, and capturing an image before fully waking the host processor, thereby reducing latency and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional wake-up schemes rely on mechanical button press to activate fingerprint sensor, then device wake-up can be triggered, but false wake-ups increase and power consumption increases

Engineering Contradiction:

Improvewake-up accuracyVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical button press system with an optical sensing system. The fingerprint sensor includes an optical sensor that detects the presence of a finger by analyzing reflected light from the display, eliminating the need for mechanical contact and enabling more accurate, false-free wake-up detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The display serves as an intermediary element that fulfills multiple functions: it provides the visual interface, acts as the illumination source for fingerprint detection, and serves as the reflective surface for optical sensing. This eliminates the need for separate mechanical buttons and dedicated illumination components.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If fingerprint sensor is integrated within active display area, then device complexity is reduced, but accurate finger detection becomes difficult without mechanical buttons

Engineering Contradiction:

Improvesensor integrationVSAvoidfinger detection accuracy

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The patent makes the display multi-functional by having it serve as both the visual display and the illumination/reflection source for fingerprint detection. This universal approach eliminates the need for separate mechanical buttons while maintaining accurate finger detection capability within the integrated display area.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The optical detection system replaces mechanical button functionality, allowing the sensor to accurately detect finger presence through optical means rather than requiring mechanical contact, thereby maintaining ease of operation despite integration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If illumination is activated before finger contact to improve detection, then detection accuracy improves, but latency increases and display visual presentation is impacted

Engineering Contradiction:

Improvefingerprint detection accuracyVSAvoidactivation latency

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary action by having the display continuously provide illumination and visual feedback in the fingerprint sensing area before actual finger contact occurs. This allows the optical sensor to be ready to detect finger presence immediately, reducing latency while maintaining detection accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The display maintains continuous illumination and visual presentation in the fingerprint area rather than activating only upon detected contact. This continuous useful action ensures that both the optical sensor and the user always have the necessary visual guidance, eliminating activation latency and maintaining smooth display presentation.

Inventive Principle:

Principle #20Continuity of useful action

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 minimizes false wake-ups and power consumption by using direct communication between touch and display controllers to illuminate the fingerprint area, guiding user finger placement and capturing high-quality fingerprint images efficiently.

Implementation Method 1

initiating illumination in the sensing region; capturing an image of the fingerprint of the finger in the sensing region

Methodology Applied

Scientific EffectLight emission from display: Light Emitting Diode

Data Source

PatentUS10592717B2Biometric imaging with hover detection

Publication Date: 2020.03.17 FINGERPRINT CARDS ANACATUM IP AB

AI summary

A method and system for fingerprint imaging in an electronic device having a display, a touch sensor with a touch interface and an optical fingerprint sensor with a sensing region is described. The method and system include placing the electronic device in a hover detect mode, the hover detect mode scanning for a hovering finger; detecting the hovering finger; initiating illumination in the sensing region to image a fingerprint of the finger; capturing an image of the fingerprint in the sensing region; and disabling the illumination in the sensing region.