Sealed Biometric Side Button With Dual Waterproof Structure

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Solution Overview

Problem

Integrating biometric input systems, such as fingerprint sensors, into portable electronic devices while maintaining a high degree of sealing against water and contaminants ingress is challenging, especially when the system requires both mechanical and electrical sealing and allows for movement.

Innovation Solution

A dual-sealed structure is implemented, featuring a button member with a chassis-mounted fingerprint sensor, sealed mechanical interfaces, and a flexible circuit element sealed within a hollow post filled with potting material, along with additional seals to prevent liquid ingress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a biometric sensing component is integrated into a button member with mechanical movement capability, then the device provides both biometric authentication and mechanical input functions, but the sealing against water and contaminants ingress becomes more difficult to maintain

Engineering Contradiction:

Improvebiometric authentication and mechanical input functionsVSAvoidsealing against water and contaminants ingress

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The button member is divided into separate functional zones: a cap portion for biometric sensing, a chassis portion for structural support, and a post for mechanical actuation. The flexible circuit element is segmented to allow movement while maintaining electrical connection. This segmentation enables each part to be optimized for its specific function while maintaining overall sealing integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A flexible circuit element with a flexible printed circuit board is used to conductively couple the biometric sensing component to internal components. The flexible nature of this circuit element allows it to accommodate the movement of the button member during mechanical actuation while maintaining continuous electrical connection, thus preserving both functionality and sealing.

Inventive Principle:

Principle #30Flexible shells and thin films

2Ease of operation

If the button member is allowed to move for mechanical input detection, then the device provides tactile feedback and button press functionality, but the electrical connection and sealing integrity become more challenging to maintain

Engineering Contradiction:

Improvetactile feedback and button press functionalityVSAvoidelectrical connection and sealing integrity

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The button member is designed with dynamic capabilities, allowing it to move between pressed and unpressed positions while maintaining functional integrity. The flexible circuit element dynamically adapts to the movement, and the input sensor detects the dynamic state changes, enabling both movement functionality and reliable electrical connection.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The flexible circuit element acts as an intermediary between the movable button member and the fixed internal components. It mediates the electrical connection while accommodating movement, and works in conjunction with the input sensor to detect button press events, thus maintaining both ease of operation and manufacturing precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If multiple sealing mechanisms are implemented to prevent liquid ingress, then the device achieves high water resistance, but the device complexity and number of components increase

Engineering Contradiction:

Improvewater resistanceVSAvoidnumber of sealing components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple sealing functions are merged into integrated components. The flexible circuit element simultaneously provides electrical connection and sealing. The button member structure itself incorporates sealing features at the interface with the housing. This merging reduces the number of separate sealing components while maintaining high water resistance.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Components are designed to perform multiple functions. The flexible circuit element provides both electrical connectivity and environmental sealing. The button member structure provides both mechanical actuation and sealing at the housing interface. This multi-functionality reduces overall device complexity while achieving reliable water resistance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP4398070B1Electronic device having a sealed biometric input system

Publication Date: 2026.03.11 APPLE INC

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AI summary

This document relates to a portable electronic device (100). The portable electronic device comprising a housing member (203) defining: a side surface of the portable electronic device (100); and a hole surface defining a hole (215) extending through the housing member (203). The portable electronic device comprising a button member (120) positioned along the side surface and defining: a chassis portion (205); and a hollow post (222) extending into the hole (215). The portable electronic device comprising a first waterproof seal (218) defined between the hollow post (222) and the hole surface; a capacitive sensing component (204) coupled to the chassis portion (205); a flexible circuit element (212) extending through the hollow post (222) and conductively coupling the capacitive sensing component (204) to at least one of a processor, a circuit board, or a conductive connector within the portable electronic device (100); and a second waterproof seal (208) defined within the hollow post (222).