Patent ID: 9408969
Filing Date: 2016-08-09
CPC Classification: A61C,A61M

Claim Text:
1. A dental anesthetic solution-filled cartridge-type motorized syringe, comprising a pinion rotated by a drive unit with a rack on a pusher rod, wherein engagement of the pinion rotated by the drive unit with the rack on the pusher rod causes the pusher rod to move, thereby moving a plunger rubber plug in a cartridge for delivery of anesthetic solution from the cartridge through a needle, characterized by comprising an extension tube movably located in a through-hole in a support block into which the pusher rod is movably inserted, and having racks formed on sides of the extension tube in alignment with the rack on the pusher rod, the extension tube comprising a forward portion having an inner diameter equal to an outer diameter of the pusher rod, a rearward portion having an inner diameter larger than the inner diameter of the forward portion, a shoulder defined between the forward portion and the rearward portion, and protrusions provided on the pusher rod adjacent the rear end of the pusher rod and adapted to abut the shoulder by moving in the rearward portion of the extension tube, thereby pulling the extension tube to engage the racks on the extension tube with the rotating pinion when the pusher rod reaches a middle of a distance equal to a length of accommodation of anesthetic solution in the cartridge, wherein the engagement of the racks on the extension tube with the pinion causes the pusher rod to move a remainder of the distance equal to the length of accommodation of anesthetic solution in the cartridge, together with the extension tube.