Fingerprint Sensor Switch Arrangement for Power Reduction

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Solution Overview

Problem

Conventional fingerprint input apparatuses face issues with high power consumption and increased component count due to the need for continuous image acquisition and software processing to determine appropriate depression pressure, which complicates configuration and affects reliability and maintainability.

Innovation Solution

A fingerprint input apparatus with a fixed sensor element and push switch or pressure-sensitive switch arranged on the opposite surface of the housing, where the switch is depressed to indicate appropriate finger depression pressure, activating the device only when necessary and eliminating the need for software image quality determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the fingerprint input apparatus continuously acquires images and uses software to determine image quality, then the apparatus can identify valid fingerprint images, but the storage capacity and processing capacity requirements increase, leading to higher power consumption

Engineering Contradiction:

Improvefingerprint image quality determinationVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the software-based image quality determination system with a mechanical switch system. The switch physically detects proper finger depression pressure and generates an activation signal, eliminating the need for continuous software processing and image quality analysis, thereby reducing power consumption while maintaining reliable fingerprint capture.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The switch system provides self-service by automatically detecting when proper finger pressure is applied and activating the apparatus only at that moment. This eliminates the need for continuous software monitoring and processing, allowing the system to remain inactive and consume minimal power until a valid input is detected.

Inventive Principle:

Principle #25Self-service

2Ease of operation

If the sensor element is held by a spring mechanism, then the sensor element can move to contact the switch, but the number of components increases and the configuration becomes complicated

Engineering Contradiction:

Improvesensor element activationVSAvoidcomponent count

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

Instead of moving the sensor element to activate the switch (as in spring-based mechanisms), the patent inverts the approach by making the switch movable relative to the fixed sensor element. The switch moves toward the sensor element when finger pressure is applied, achieving the same activation function with a simpler fixed sensor mounting.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts the spring mechanism from the sensor element assembly, separating the sensing function (fixed sensor element) from the activation function (movable switch). This extraction eliminates the need for springs and complex mounting mechanisms, reducing component count while maintaining operational ease.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If the sensor element moves to depress the switch, then the detection signal can be generated, but clearances and movable mechanisms are required, increasing apparatus size and reducing waterproofness

Engineering Contradiction:

Improvedetection signal generationVSAvoidwaterproofness and dustproofness

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the movement direction: instead of the sensor element moving toward the switch, the switch moves toward the fixed sensor element. This inversion allows the sensor element to remain firmly fixed in the housing, eliminating clearances and improving waterproofness while still generating the detection signal when the switch contacts it.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The switch uses a flexible elastic body that can deform to contact the sensor element when finger pressure is applied. This flexible mechanism eliminates the need for rigid clearances and movable mounts, allowing for a more sealed, waterproof construction while maintaining reliable detection signal generation.

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentUS7555150B2Fingerprint input apparatus

Publication Date: 2009.06.30 NEC PLATFROMS LTD

AI summary

This invention provides a fingerprint input apparatus which detects that a finger is put on a sensor element, which can reduce power consumption, which requires fewer components, and which is simple in configuration. In a fingerprint input apparatus which includes a sensor element for reading a fingerprint and a switch for detecting that a finger is put on the sensor element, which is activated by an operation of the switch the switch is a push switch, the sensor element and the switch are fixed to a housing, and the switch is arranged on an opposite surface to a surface on which the sensor element is arranged, across the housing. The switch may be a pressure sensitive switch instead of a push switch, and the apparatus may further include a unit for notifying a user whether it is appropriate to apply a depression pressure.