Patent ID: 6179569
Filing Date: 2001-01-30
Classification: A61M

Abstract:
A liquid infusion apparatus including means for fixing an outer cylinder of a syringe and driving means including a motor, a plurality of gears, a feed screw, a carriage and a slider coupled to the carriage for pushing a plunger in a predetermined direction, thereby exhausting liquid in the syringe, the improvement comprising:an incremental linear encoder having a plate parallel to the feed screw, a first detection sensor mounted on the carriage that is engaged with the slider, a second detection sensor mounted at an end of the outer cylinder, and a dog mounted on the carriage and configured to actuate the second detection sensor by movement of the carriage;an encoder output processing circuit configured to process a first signal generated between the plate and the first detection sensor representing a position of the carriage;a sensor output processing circuit configured to process a second signal generated by the detection of the dog by the second detection sensor; anda feedback processor configured to process the first and the second signals and to generate a position signal based on the first and the second signals, wherein the position signal represents the absolute position of the plunger.