Disposable safety syringe

A disposable safety syringe, comprising:

• a) a cylindrical syringe barrel;
• b) an injection needle integral with a needle-carrier attached to a fore end of the syringe barrel;
• c) a plunger slidable in the syringe barrel, an injection stroke on the plunger extending from a retracted maximum syringe-filling position, liquid medicine aspired to a forwardmost position, and a manually drivable stem fitted on a rear of the plunger extending through the open rear end of the syringe barrel thereof;
• d) a needle-covering sleeve axially fitted on the syringe barrel slidable from a retracted rest position for leaving the needle exposed to an advanced safety position for entirely covering the needle;
• e) plunger-clamping means, consisting of hook-like interacting means provided at the rear of the syringe barrel, the clamping means being initially engaged with the needle-covering sleeve for retaining the needle-covering sleeve in the retracted rest position, the stem on the plunger automatically disengaging the clamping means in an end portion of the injection stroke of the plunger thereby releasing the needle-covering sleeve;
• f) a spring releasably attached to the interacting means and interposed between the rear of the syringe barrel and the needle-covering sleeve for moving the needle-covering sleeve towards the advanced safety position, the needle-covering sleeve adapted for elastically adhering to a patient body, and then progressively advancing even after extracting the needle from the patient body after injection of the medicine until the needle is entirely covered by the needle covering sleeve;
• g) the needle-covering sleeve further comprises a rear rim shaped as an outwardly projecting hook-like tooth and cooperating with at least one complementary inwardly projecting hook-like tooth provided on retaining tongues, the teeth extending forwardly in a longitudinal direction of the syringe from a head at the rear end of the syringe barrel, wherein the teeth are automatically movable from a radially retracted hooking position, when the teeth hook the rim of the needle-covering sleeve for holding the sleeve in the retracted rest position, to a radially opened out releasing position, in which the teeth are released from the rim of the needle-covering sleeve for disengaging the sleeve;
• h) a rear end of the stem having cooperating means which cooperate with the retaining tongues and automatically cause the tongues to move from radially retracted hooking positions to radially opened out releasing positions when the injection stroke of the plunger ends;
• i) the needle-carrier having at least one lateral locking projection projecting radially outwards and slidably engaging in a longitudinal slot in the needle-covering sleeve, automatic stop means on a rear end of the slot engaging the lateral locking projection for preventing any axial movement thereof with respect to the needle-covering sleeve in the advanced safety position thereof, thus securing at least the needle-carrier to the needle-covering sleeve.