Multidose jet injector

Claim 1

AN EJECTOR INSTRUMENT COMPRISING A HOLLOW BODY CLOSED AT ITS FORWARD END WITH A CYLINDRICAL BLOCK CONTAINING A MEDICAMENT CHAMBER, A MEDICAMENT RESERVOIR MOUNTED ON SAID BODY, A NOZZLE MOUNTED ON THE OUTER END OF SAID BLOCK, A FIRST BORE BETWEEN SAID NOZZLE AND SAID MEDICAMENT CHAMBER, A SECOND BORE BETWEEN SAID FIRST BORE AND SAID MEDICAMENT RESERVOIR, A ROTARY VALVE MEMBER IN SAID FIRST BORE FOR ESTABLISHING COMMUNICATION BETWEEN SAID MEDICAMENT CHAMBER AND SAID RESERVOIR IN ONE POSITION AND BETWEEN SAID MEDICAMENT CHAMBER AND SAID NOZZLE IN ANOTHER POSITION, A PLUNGER CARRIED WITHIN SAID BODY HAVING AN ENLARGED REAR CUP-LIKE SPRING SEAT AND A HEAD WITHIN SAID CHAMBER FOR EXPELLING MEDICAMENT THROUGH SAID NOZZLE, A PISTON SLIDABLY MOUNTED IN THE OTHER END OF SAID BODY, SPRING MEANS PRECOMPRESSED BETWEEN SAID SPRING SEAT AND SAID PISTON, A LINK CONNECTED TO SAID PLUNGER TO MAINTAIN SAID SPRING IN A PRECOMPRESSED STATE, A LATCH MOUNTED AT A PREDETERMINED POINT ON SAID BODY ADJACENT SAID PLUNGER TO LOCK SAID PLUNGER AGAINST FORWARD MOVEMENT, AND FITTING MEANS WITHIN SAID BODY BEHIND SAID PISTON FOR CONNECTING TO A SOURCE OF PRESSURIZED FLUID FOR ADVANCING SAID PISTON TO ADDITIONALLY COMPRESS SAID SPRING MEANS, WHEREBY UPON RELEASE OF SAID LATCH SAID SPRING EXPANDS TO IMPART THE INITIAL ADVANCING FORCE TO THE PLUNGER AND SAID PISTON CONTINUES TO APPLY THE ADVANCING FORCE FOR EJECTING THE MEDICAMENT.