Infusion syringe pump

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION The infusion injection pump comprises a motor-gear unit 1 which drives a threaded spindle 2 which projects from an end face of the motor-gear unit 1 and on which a linearly movable drive member 3 is disposed.
The infusion syringe 4 consists of a syringe cylinder 5 and a syringe plunger 6 having a plunger rod 7.
The front end of the syringe cylinder 5 is inserted into a holder 8 which in the case of the example is mounted on the motor-gear unit 1 of the infusion syringe pump.
The rear end of the plunger rod 7 is inserted into a further holder 9 which is disposed on the linearly movable drive member 3.
If the linearly movable drive member 3 is moved in the direction towards the motor-gear unit 1 the syringe plunger 6 in the syringe cylinder 5 is displaced and the injectate is expelled through the syringe outlet 10.
The syringe outlet is connected via a (not shown) flexible tube to the patient.
Such an infusion syringe pump is described in DE-OS 3,428,655, to the disclosure of which reference is made.
A position-defining element 11 is arranged on the linearly movable drive member 3 in such a manner that said element is coupled functionally to an absolute displacement pickup 12, in particular is in engagement therewith.
Said absolute displacement pickup 12 is constructed in a particular embodiment of the invention as linear potentiometer as shown in the drawing.
The absolute displacement pickup 12 may also be formed by a known inductive capacitive or magnetic position-indicating element.
As also apparent from the drawing the absolute value pickup 12 extends parallel to the longitudinal axis of the threaded spindle 2 or to the displacement direction of the drive member 3.
Furthermore, the absolute displacement pickup 12 is connected to an evaluating unit 13 via the line 14 which in turn is connected via a line 15 to the motor-gear unit 1.
Likewise, the ends of the linear potentiometer are connected via the lines 14 to the evaluating unit 13 and form together with the position-defining element 11 a voltage divider, said element 11 being formed as wiping contact