| 摘要 |
Provided is an anesthetic solution-filled cartridge-type electric dental syringe, wherein the plunger has been shortened but the plunger can nevertheless be extended to the distance necessary to evacuate the anesthetic solution from the cartridge. The syringe comprises: an extension tube (11) into which a plunger (5) is movably inserted, the extension tube being movably disposed in the through hole (14) of a support block (13) and having racks (15, 15) formed in the side surface thereof that are coordinated with the racks (9) of the plunger; and a means for the plunger to draw the extension tube to engage the racks (15, 15) of the extension tube with a pinion (21) when the plunger reaches the middle of the distance corresponding to the anesthetic solution accommodation length of the cartridge. By the engagement of the racks of the extension tube with the pinion, the plunger moves together with the extension tube for the remainder of the distance corresponding to the anesthetic solution accommodation length of the cartridge. |
