Abstract: A disposable pumping cassette having an integral auxiliary flow control and pressure monitoring member is used for delivering a medicinal fluid to a patient. The pumping cassette includes an elastomeric member mounted in a rigid body having an inlet and an outlet. An inlet valve and an outlet valve on the cassette are opened, and the flow control is positioned to allow the medicinal fluid to flow freely through the cassette, priming it before the outlet is connected to the patient. The cassette is then coupled to an associated pump driver, closing the flow control to disable free fluid flow through the cassette, and the outlet to the cassette is coupled in fluid communication with the patient's body.

Abstract: A speed control circuit for a DC motor includes a digital-to-analog (D/A) converter, a regulator/controller, and a control circuit which applies a compensating current to the DC motor that compensates for variations in loading applied to the motor. The regulator/controller compares a reference voltage provided by the D/A converter with a feedback signal provided by the motor to generate a signal to activate the control circuit, thus to supply a compensating current to the motor.

Abstract: A disposable pumping cassette having an integral auxiliary flow control and pressure monitoring member is used for delivering a medicinal fluid to a patient. The pumping cassette includes an elastomeric member mounted in a rigid body having an inlet and an outlet. An inlet valve and an outlet valve on the cassette are opened, and the flow control is positioned to allow the medicinal fluid to flow freely through the cassette, priming it before the outlet is connected to the patient. The cassette is then coupled to an associated pump driver, closing the flow control to disable free fluid flow through the cassette, and the outlet of the cassette is coupled in fluid communication with the patient's body. The medicinal fluid is drawn into a pumping chamber formed in the rigid body as a plunger of the associated pump driver is drawn up from the elastomeric membrane at a recess formed in the rigid body.

Abstract: An improved rotor for use with a segmented peristaltic cartridge comprising a housing and a cover for assembly, said assembled housing and cover defining a pumping chamber which holds the improved rotor, a rotor sleeve and a section of flexible tubing wrapped around the rotor and connected to respective inlet and outlet ports of the cartridge. The flexible rotor includes an eccentric structure wherein flexible beam members provided on an outer surface of the rotor form a compliant member which improves the flexibility of the rotor assembly to avoid excessive compression loads or high torque and/or dynamic leak back or low torque for the tubing in the cartridge.

Abstract: A method and apparatus for continually measuring the specific gravity of a flow liquid. The liquid is caused to flow across a flat measurement surface defined by a light transmissive shelf member. The measurement surface, i.e. the interface between the shelf member and liquid sample thereon, is illuminated by rays incident at angles greater than and less than a critical angle to reflect a boundary line whose position is dependent on the critical angle and thus the specific gravity of the liquid sample. The reflected boundary line is projected onto a photovoltaic surface which, together with detector electronics, determines the position of the boundary line with respect to a boundary line position associated with a reference liquid. The difference in boundary line position is used by the detector electronics to determine the specific gravity of the sample by a table lookup procedure.

Abstract: The principal of total internal reflection is utilized in sounding an alarm in a medical fluid infusion system when a downstream blockage occurs. A miniature prism is mounted in a cavity in a rigid exterior tube. The infusing fluid flows in a plastic tubing along the central channel of the rigid tube. The plastic tubing in the interior of this exterior rigid tube is diametrically expansive with an unpressurized outside diameter which is less than the inside diameter of said rigid exterior tube. A light source and light detector is positioned adjacent to the equilateral planes of the prism mounted in the rigid tube.

Abstract: A digital servo control system for a d.c. motor to achieve stepping motor precision and a wider speed control range than either a conventional d.c. motor or a stepping motor, as may be typically utilized in an IV syringe pump. Motor position and direction sensing, as well as motor advance signals at the desired motor rate, condition motor advance and retard logic which, in turn, effects a unique counter-controlled motor drive subsystem to cause the d.c. motor to move forward, reverse, coast or slow down over a 1,000 to 1 speed control range.

Abstract: An analog-to-digital converter includes a first and a second comparator. The first comparator generates a plurality of quantizing outputs defining voltage gaps and also has first and second reference current outputs whose magnitudes are representative of which voltage gap encompasses the analog input voltage and a third reference current output whose magnitude is representative of the voltage gap width. A first encoder receives the quantizing outputs of the first comparator and generates a binary number which represents which of the voltage gaps the analog input voltage is encompassed by. The reference current outputs of the first comparator are input to a reference voltage level shifting circuit whose shifted reference output voltage is provided as an input to a second comparator which compares the analog input with a plurality of internal reference voltages which form a second continuous range of voltage gaps.

Abstract: An analog-to-digital converter includes a first comparator which receives an analog input. The first comparator generates a plurality of reference voltages which establish a first continuous range of voltage gaps. The first comparator has a plurality of quantizing outputs, one of which will be at a logical one and the rest of which will be at logical zeros in order to indicate which of the voltage gaps encompasses the analog input voltage. The first comparator also has a reference current output whose magnitude is representative of which voltage gap encompasses the analog input voltage. A first encoder receives the quantizing outputs of the first comparator and generates a binary number which represents which of the voltage gaps the analog input voltage is encompassed by and which constitutes the most significant bit group of the binary digital representation of the analog input voltage. A voltage subtractor circuit receives as inputs the reference current output of the first comparator and the analog input.

Abstract: An analog-to-digital converter includes a first and a second comparator each of which receives an analog input. The first comparator generates a plurality of reference voltages which establish a first continuous range of voltage gaps. The first comparator has a plurality of quantizing outputs, one of which will be at a logical one and the rest of which will be at logical zeros in order to indicate which of the voltage gaps encompasses the analog input voltage. The first comparator also has first and second reference current outputs whose magnitudes are representative of which voltage gap encompasses the analog input voltage and a third reference current output whose magnitude is representative of the voltage gap width.

Abstract: A high-speed voltage subtractor circuit suitable for use in a serial-parallel A/D converter uses differential current switches to select a predetermined reference voltage value as one input to a precision current matching circuit whose other input is an applied analog input signal. An output buffer circuit coupled to the current matching circuit produces an output signal equal to the difference between the analog input signal and the reference voltage value.