Abstract: A first sensor (13-1), the mounting position of the first sensor (13-1) being recognized as a counting number of instruction pulses to a pulse motor (3), is arranged along a plate (11) with slits of an encoder at a portion between a position where a pushing holder (7) is connected to a plunger (9) for the liquid infusion, and a start position where the pushing holder (7) is separated from the plunger (9). A counting means (16) for counting encoder pulses from the encoder, is reset when a first sensor (13-1) is detected by a position detecting device (14) moved together with the pushing holder (7), and started to count the encoder pulses according to the movement of the pushing holder (7). A time to complete the liquid infusion is calculated by using a distance between the position where the plunger (9) is connected to the holder (7) and a liquid infusion finish position proper to the syringe, and a predetermined liquid infusion speed.

Abstract: A liquid infusion apparatus for fixing an outer cylinder of a syringe and a driver for pushing a plunger in a predetermined direction so as to exhaust liquid in the syringe, an incremental linear encoder arranged along the feeding axis of said driver for pushing the plunger, a detector of said incremental linear encoder mounted on a slider portion of the driver for pushing the plunger so as to generate a signal indicating a moving quantity of the plunger, and a sensor provided in the vicinity of a liquid exhaust port of the outer cylinder for setting along the feeding axis a remaining liquid quantity small section so as to generate a signal about a position of the plunger at the remaining liquid quantity small section.

Abstract: A first sensor (13-1), the mounting position of the first sensor (13-1) being recognized as a counting number of instruction pulses to a pulse motor (3), is arranged along a plate (11) with slits of an encoder at a portion between a position where a pushing holder (7) is connected to a plunger (9) for the liquid infusion, and a start position where the pushing holder (7) is separated from the plunger (9). A counting means (16) for counting encoder pulses from the encoder, is reset when a first sensor (13-1) is detected by a position detecting device (14) moved together with the pushing holder (7), and started to count the encoder pulses according to the movement of the pushing holder (7). A time to complete the liquid infusion is calculated by using a distance between the position where the plunger (9) is connected to the holder (7) and a liquid infusion finish position proper to the syringe, and a predetermined liquid infusion speed.

Abstract: In a liquid infusion apparatus, an incremental linear encoder is arranged along the feeding shaft direction of the liquid infusion apparatus to directly monitor the movement and position of a carriage part which applies an action to a plunger. A detecting sensor is provided at a starting point of a remaining liquid quantity small region to recognize the absolute position at said region by using feed-back pulses from said encoder. A pressing device for pressing a flange of the plunger to a plunger receiving portion of a slider by holding arms is provided. A pressure sensor is arranged between said plunger receiving portion and the slider to detect a negative pressure applied to the plunger in such a manner that the other operation states of pressure are detected based on a detected value of pressure at which the flange is pressed to the plunger receiving portion.