Transparent Syringe Barrel Scale Structure for Accurate Dose Alignment
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Solution Overview
Problem
Existing syringe barrels made of transparent resins face issues with low visibility of scales due to inconspicuous concavo-convex shapes, and conventional label wrapping methods result in inaccurate scale markings.
Innovation Solution
A syringe barrel with a stepped structure on the inner circumferential surface, featuring protrusions or grooves that provide high visibility and accurate scale alignment, even when made of transparent materials like cyclic olefin polymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a label is wrapped on the barrel to provide the scale, then the scale can be provided on the barrel, but the accuracy of the scale is low
Solution Approach 1:
The patent merges the scale marking function with the barrel structure itself by forming the scale as a concavo-convex shape directly on the barrel surface through molding. This integration eliminates the separate label wrapping process and ensures high accuracy because the scale becomes an inherent part of the barrel geometry rather than a separate applied element.
Solution Approach 2:
The patent replaces the mechanical process of label wrapping and adhesive application with a molding process that forms the scale directly into the barrel. This substitution of the manufacturing mechanism achieves both high scale accuracy and manufacturing efficiency by using the barrel molding process itself to create the scale features.
2Measurement precision
If a concavo-convex shape is formed on the barrel surface by molding to attach the scale with high accuracy, then the scale accuracy is improved, but visibility is poor because the scale is inconspicuous when the barrel is made of transparent resin
Solution Approach 1:
The patent changes the physical parameters of the scale features by controlling the depth, width, and shape of the concavo-convex formations. By optimizing these geometric parameters, the scale creates sufficient optical contrast against the transparent barrel material, making the markings visible while maintaining the high accuracy benefits of the molded-in approach.
Data Source
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AI summary
A barrel (12) of a prefilled syringe (10) has a hollow body portion (18) configured such that a gasket (16) is slidably inserted. The barrel (12) is made of a resin having a total light transmittance of 80% or more in a measurement method according to ASTM-D 1003. A scale (38) is provided on an inner circumferential surface (12a) of the body portion (18). The scale (38) is formed by a stepped structure (40A) having a step height of 0.001 to 0.15 mm in a radial direction.