Needle Safety Shield Release Mechanism for Low-Force Activation

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Solution Overview

Problem

Existing safety devices for medical needles require high user effort to transition from a storage position to an operative position, posing a risk of unintentional activation and complicating the operation.

Innovation Solution

A safety device with a retaining system and releasing system, activated by inward pressure on the protective cap, allows easy transition from a storage to an operative position without requiring significant effort, using a ring, protective shield, and protective cap with cooperating retaining and releasing mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a retaining system is provided to prevent unintentional movement of the protective shield, then safety is improved, but the force required to activate the shield increases

Engineering Contradiction:

ImprovesafetyVSAvoidactivation force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The retaining system is divided into two separate retaining portions: a first retaining portion on the protective shield and a second retaining portion on the protective cap. This segmentation allows the retaining function to be distributed, enabling easier activation when the cap is removed while maintaining safety during storage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The protective cap is pre-mounted on the protective shield in a nested configuration before use. This preliminary arrangement ensures that the retaining portions are already positioned to prevent unintentional movement, while also being prepared to release the shield easily when the cap is removed for activation.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If the protective cap is mounted on the protective shield, then the retaining system is simplified, but the cap may accidentally disengage during use

Engineering Contradiction:

Improveretaining system complexityVSAvoidcap retention reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The retaining portions act as intermediary elements between the protective cap and protective shield. These intermediaries provide a controlled connection that simplifies the overall structure while maintaining reliable retention through the cooperating geometry of the retaining portions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Instead of using a complex locking mechanism to prevent cap disengagement, the design uses a simple nested mounting where the cap naturally retains the shield through its geometry. The retention reliability is achieved by inverting the approach: rather than actively locking, the system passively retains through the cap's structure until intentionally activated.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS12508373B2Safety device for preventing needle stick injury with a needle of a medical injection device

Publication Date: 2025.12.30 BECTON DICKINSON & CO

AI summary

A safety device includes a ring configured to be attached to a distal tip of a medical injection device and a protective shield movably coupled to the ring and configured to adopt a storage position covering the needle tip, an operative position uncovering the needle tip, and a safety position covering the needle tip A protective cap is mounted on the ring to cover the needle tip, and can be separated from the ring prior to use of the device. A retaining system includes a first retaining portion on the protective shield and a second retaining portion on the protective cap, with the first and second retaining portions cooperating in the storage position to prevent the protective shield from moving to its operative position. A releasing system releases the retaining system and is configured to be activated by a manual inward pressure exerted on the protective cap.