Injection device for dental anesthetic or like

Claim 1

In an injection device for a dental anesthetic or the like, having a rear end side of an operating rod accommodated in a main body including a handle portion in an axially cylindrical form and an operating portion case connected to the upper portion of the handle portion to allow a front end side of said operating rod to go in and out toward a cavity of a cartridge holder detachably connected to a front end of said operating portion case, a drive mechanism operated by a motor contained in the main body linked to the operating rod, a drive switch for controlling the motor to allow said motor to normally rotate and a reverse rotation switch for controlling said motor so as to allow said motor to reversely rotate, said drive switch and said reverse rotation switch provided on the outside face said main body, an injection needle having a communicating needle provided at a base end side, said injection needle detachably connected to a front end of said cartridge holder, said communicating needle extending through a membrane at a front end of a cartridge when housed in said cartridge holder, and a hook portion on the front end of said operating rod abutting a piston in a rear end side of said cartridge, an improvement of said injection device comprising, manipulation means located between the drive mechanism and the operating rod for selectively engaging or disengaging the drive mechanism to and from the operating rod, said manipulation means including actuating means on an outside face of the main body for permitting an operator to selectively engage or disengage the drive mechanism to and from the operating rod, wherein when the drive mechanism and the operating rod are disengaged the operating rod can be manually moved to quickly accommodate replacement of a used cartridge.