An improved barrel type plunger for use with a needle-retractable safety syringe and the syringe using the same

摘要

The present invention provides an improved barrel type plunger for use with a needle-retractable safety syringe, comprising a barrel, a needle retracted trigger and a supporting member. A front portion of said barrel is fitted over a sealing rubber pad, a slotted hole is provided at a wall of the front portion of said barrel, a bearing piece is provided in said slotted hole, and one end of said bearing piece is connected to the front side wall of said slotted hole. Said barrel and said supporting member are provided with a snap-in structure, respectively, which make supporting member releasably engaged in said barrel. After having released from said barrel, said supporting member is able to translate backwards under the action of a needle retraction force so that said bearing piece can be returried to such a position that said needle can be retracted backwards to the interior of said barrel. The present invention further provides a syringe comprising the above-mentioned barrel type plunger. The barrel type plunger and syringe according to the present invention have relatively simple and reasonable structures, are easy to produce and make the controllable retraction of the needle more convenient. Because of more compact structures, the barrel type plunger and syringe according to the present invention are suitable for a minor volume syringe with a thinner syringe barrel.