Filter syringe

Claim 1

In a syringe for the injection of a liquid including a vial having an open end through which the liquid is to be ejected from the vial and a plunger axially displaceable in said vial for displacement of liquid through the open end, a rupturable diaphragm extending across the open end of the vial in sealing relation therewith, a hollow injection needle having inner and outer pointed ends endwise aligned with the open end of the vial and mounted for endwise movement between retracted position with the inner end of the needle spaced a short distance beyond the diaphragm and operated position with the inner end of the needle piercing the diaphragm, the improvement which comprises a filter member spanning the open end of the vial between the end of the vial and the diaphragm, said diaphragm constituting a member separate and apart from the filter, a well in the diaphragm extending from the side adjacent the filter member partially through the diaphragm in endwise alignment with the needle and into which the inner end of the needle extends when in operated position and stop means mounted intermediate the needle ends, whereby in the operated position the inner needle end will extend through the diaphragm but not pierce the filter.