US 5,236,416 A · Syringe plunger position detection and alarm generation

Abstract

A syringe plunger position detection and alarm system continuously determines the position of a syringe plunger and provides near end of travel and end of travel alarms. Plunger movement is also monitored and if movement is less than a calculated amount, an alarm is provided. A variety of syringes of different sizes is usable. A potentiometer is mounted along the line of travel of the screw drive mechanism and a marker is mounted to extend from the screw mechanism to the potentiometer to force an internal contact in the potentiometer. The voltage provided by this internal contact is analyzed by the process to derive absolute and relative position of the plunger. The end of travel position of each plunger is stored in processor memory and from the operator input rate of infusion, the characteristic curve of the potentiometer also stored in memory, the plunger displacement of the syringe, and the time of the near end of travel alarm, the voltage of the near end of travel position is calculated. The potentiometer is self-contained and sealed.

Claims28

Dependent claims

An apparatus for determining the position of a plunger of a syringe, comprising:

a position marker coupled to and moving with said plunger;
stationary detector means, said position marker means being coupled mechanically and non-electrically to said stationary detector means for linear movement relative thereto, said stationary detector means for providing a position signal in response to said linear movement of said position marker relative to said stationary detector means, said position signal differing for different positions of said position marker along said stationary detector means;
and
processor means for receiving said position signal and for determining an absolute position of the plunger in response thereto, said processor means monitoring said position signal over a pre-determined unit of time, comparing said received position signals, and based on said comparison, determining if movement of the said drive means is occurring.

1 more element

A plunger position determination apparatus for determining the position of a plunger which is disposed within an enclosure, said plunger having an end of travel position at which it is driven into the enclosure to a predetermined position and a starting position at which it is in a retracted position in the enclosure, the apparatus comprising:

a plunger driver coupled to the plunger and moving the plunger from the starting position to the end of travel position;
a position marker fixedly coupled to and moving with said plunger driver;
a stationary detector mechanically and non-electrically coupled to the marker and which provides a position signal in response to said coupling, the position signal being different for different coupling positions of the marker along the detector, the position signal changing in response to movement along the detector;
and
a processor which receives the position signal and determines the absolute position of the marker in response thereto, and which receives position signals over a predetermined unit of time from the detector and determines if movement of the plunger driver is occurring.

2 more elements

An apparatus for determining the position of a drive mechanism, said drive mechanism including drive means for providing a movement force to the drive mechanism, and engagement means for engaging said drive mechanism and moving in response thereto, said engagement means being movable relative to said drive means, and, said element for determining position of a drive mechanism having:

a position marker fixedly coupled to and moving with said engagement means;
a stationary detector means mechanically and non-electrically coupled to said position marker for generating a position signal responsive to relative movement of said position marker with respect to said stationary detector means;
and
processor means for receiving said position signal and determining the absolute position of said position marker means relative to said stationary detector means responsive to said position signal, said processor means receiving position signals over a pre-determined unit of time, comparing said position signals, and determining if movement of the said drive means is occurring based on said comparisons.

1 more element

Dependencies are inferred from the claim text.

Syringe plunger position detection and alarm generation

Life of this patent

Syringe plunger position detection and alarm generation

Life of this patent

Abstract

Claims28