A single use syringe with plunger arm safety cover comprises a plunger arm, a plunger tip, a syringe body, and a tip retaining sleeve. The tip retaining sleeve is surroundingly disposed around a protruding tip of the plunger tip, so as to make the protruding tip retaining arms to be engaged to the plunger arm. When a user pulls back the plunger arm, sleeve ribs on the tip retaining sleeve is locked to the syringe body so as to constrain the tip retaining sleeve to be pushed forward again. At this moment, if the use pushes the plunger arm, the protruding tip will start to separate from a sleeving range of the tip retaining sleeve to make the plunger arm and the plunger tip to separate from each other. When the plunger arm and the plunger tip are separated from each other, they cannot be engaged with each other again so that the syringe cannot be repeatedly used. Further, for a used syringe, the plunger arm thereof is removed from the syringe body and is coupled to a positioning lock of the body, while the plunger arm covers the needle of the used syringe, so as to effectively prevent the risk of an exposed needle accidently contacting human body.一種具有活塞臂安全蓋之一次性注射器,包含一活塞臂、一活塞端、一注射器本體以及一固定套筒。固定套筒係環繞設置於活塞端的突出尖端周圍,藉此使得突出尖端卡合於活塞臂。當使用者回拉活塞臂,固定套筒上的套筒凸肋將卡掣於注射器本體,藉此限制固定套筒再次被往前推動。此時若使用者推壓活塞臂,則突出尖端將開始脫離固定套筒的套設範圍,以使得活塞臂與活塞端二者分離。當二者分離之後,活塞臂與活塞端將無法再次卡合,使得注射器無法被重複使用。並且,使用過後的注射器,其活塞臂係自注射器本體內卸除,並接合於本體上的一定位鎖,此時活塞臂覆蓋住注射器之針頭,藉此有效防範曝露針頭誤觸人體的危險。10...具有活塞臂安全蓋之一次性注射器160...通道170...鎖合部430...針頭
