Safety Injection Needle Assembly With Dual-Sheath Locking

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Solution Overview

Problem

Existing dental injection needles lack user-friendly safety features to prevent accidental needlestick injuries and ensure sterility, with existing solutions being either expensive or not suitable for narrow or less accessible areas, and lacking temporary locking mechanisms and indicators for user convenience.

Innovation Solution

A safety injection needle assembly with a double-layer sheath system, comprising an inner sheath for housing the needle and an outer sheath for full envelopment, along with temporary and permanent locking mechanisms, and indicators for user guidance, allowing controlled needle exposure and safe disposal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single-layer sheath is used to house the injection needle, then the device structure is simple, but the protection against needlestick injuries and sterility maintenance are insufficient

Engineering Contradiction:
Improveprotection against needlestick injuriesVSAvoidsheath structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a double-layer sheath structure where an inner sheath houses the injection needle and an outer sheath envelops the inner sheath. This nested configuration provides enhanced protection against needlestick injuries and maintains sterility without requiring complex additional mechanisms, as each sheath layer performs its protective function independently within the nested arrangement.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Ease of operation

If a permanent locking mechanism is used to control needle shield position, then the needle protection is reliable, but the user cannot control needle exposure during injection

Engineering Contradiction:
Improveneedle exposure controlVSAvoidneedle protection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent employs a dynamic locking mechanism with a movable locking member that can transition between locked and unlocked states. During injection, the locking member can be moved to unlock the needle shield, allowing controlled needle exposure. After injection, the locking member returns to the locked position to provide reliable needle protection. This dynamic behavior enables both user control during operation and reliable protection when not in use.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The needle shield is pre-configured in a locked position that covers the injection needle before use. The locking mechanism is designed to maintain this preliminary protected state until the user intentionally activates the unlocking action, ensuring automatic safety without requiring user intervention until needed.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If no indicator is provided for locking mechanism position, then the device structure is simpler, but the user cannot easily determine the current state

Engineering Contradiction:
Improvelocking position identificationVSAvoidindicator mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent incorporates visual indicators that change appearance based on the locking mechanism position. When the locking member is in the locked position, an indicator (such as a window or visible marker) displays a specific visual state. When unlocked, the indicator displays a different visual state, enabling users to easily determine the current locking status without adding complex mechanical feedback mechanisms.

Inventive Principle:
Principle #32Color changes

4Adaptability or versatility

If a pre-filled syringe is retained within the safety device, then the injection process is simplified, but the device cannot be used for narrow or less accessible areas

Engineering Contradiction:
Improveaccessibility to narrow areasVSAvoidinjection process
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent separates the safety device into modular components: the needle assembly with locking mechanism and the syringe. This segmentation allows the needle portion to be used independently for injections in narrow or difficult-to-reach areas, while the syringe can be attached when larger volume injections are needed. The receiving means on the hub allows optional syringe attachment, providing versatility for different clinical scenarios.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4034200B1A safety injection needle assembly
Publication Date: 2026.03.25 TAY KENG KIONG
  • EP4034200B1 patent drawingFigure 1
  • EP4034200B1 patent drawingFigure 2~3(c)
  • EP4034200B1 patent drawingFigure 4

AI summary

The present invention relates to a safety injection needle assembly (100) comprising an injection needle (110) affixed to a hub (120) having a stud (130) and a receiving means (140) for receiving a dental syringe, an inner sheath (150) having a slit (190) to receive the stud (130) for retaining the injection needle (110), and an outer sheath (220) and a cap (240) for housing the inner sheath (150). In addition, a pair of outer studs (170) of the inner sheath (150) complements with an outer sheath inlet (230) and a cap inlet (250) for removably engaged and locked via locking means (210). The slit (190) comprises a plurality of terminal ends (200) for receiving and locking the stud (130) via the locking means (210). Preferably, the safety injection needle assembly (100) comprises a sealing member (260) having two set of indicators (280) for indicating position.