Patent ID: 8491522

Claim:
A computer controlled electric syringe comprising: a piston unit comprising: a piston comprising a first end, a second end and a hollow portion communicating with an opening formed at the first end, the piston being configured to press and move a rubber plug of a cartridge, in which a medicinal solution is enclosed, by the second end to discharge the medicinal solution from the cartridge through an injection needle; a ball screw comprising a screw shaft and a nut portion that is screwed into the screw shaft, the screw shaft being loosely inserted into the hollow portion of the piston through the opening, the nut portion being coupled to the piston; a screw shaft supporting portion rotatably supporting the screw shaft of the ball screw; a rotation preventing portion configured to prevent the nut portion of the ball screw from being rotated; and a piston supporting portion supporting the piston to be movable in an axial direction of the screw shaft along with the nut portion by the rotation of the screw shaft.