Position control for plunge mechanism

摘要

Methods and apparatus for controlling the position of a plunge mechanism which is mounted to a cartridge engaging assembly are disclosed herein. In one embodiment, a cartridge engaging assembly includes a plunge mechanism which is mounted to the cartridge engaging assembly. The plunge mechanism is movable between a retracted position and an extended position. A reference mark is provided on the plunge mechanism so that the reference mark moves with the plunge mechanism. A detector is also mounted to the cartridge engaging assembly. As the plunge mechanism is extended, the detector detects the reference mark and produces an output signal which is related thereto. A control system is operatively associated with the detector and is responsive to the output signal produced thereby. The control system is also operatively associated with the plunge mechanism. As a result, the control system can regulate the position of the plunge mechanism based on the output signal produced by the detector.