Patent ID: 7303545

Claim:
A butterfly-needle assembly comprising: an elongated and generally U-section lower case part having a pair of longitudinally extending vertical side walls; an elongated upper case part extending longitudinally along the lower part and forming a pair of transversely open slots with the side walls thereof, the case parts together forming an elongated hollow case; an elongated needle in the case and having a pair of generally coplanar and oppositely projecting wings extending out of the case through the slots, the slots being sufficiently long that the needle can move longitudinally between a front position with the needle projecting substantially from a front end of the case and a rear position with the needle completely within the case; an elastically deflectable spring element projecting at a small acute angle toward a rear end of the case into one of the slots, extending at least partially across and blocking the one slot rearward of the respective wing in the front position of the needle, and directed to be deflected elastically by the respective wing and allow the needle to move from the front position into the rear position and to block movement of the needle from the rear position into the front position; a case formation projecting transversely inwardly into the case; and a needle formation projecting transversely outwardly from the needle opposite to the case formation and being longitudinally engageable with the case formation on shifting of the needle between its position, the case and needle being sufficiently elastically deformable that the formations can push longitudinally past each other on longitudinal shifting of the needle between its positions, the formations being positioned to retain the needle in the front position and prevent displacement of the needle forward out of the case.