Abstract: The present invention provides an improved, low cost method and apparatus for monitoring the intravenous metering of fluids to a patient. The present invention provides a strain gauge which is preferably a balanced metal beam. Conditioning circuitry is provided which has as input the strain gauge output. The output of the conditioning circuit is inputted into occlusion sensing circuit. The output of occlusion sensing circuit is inputted into an air sensing circuit. The output of both the occlusion sensing circuit and the air sensing circuit are inputted into an analog to digital convertor which is monitored by a microprocessor for abnormal signals.

Abstract: A rotary encoder comprises a rotary plate having a plurality of primary slits defined in the rotary plate in a circular row coaxial with the axis of rotation of the rotary plate. The rotary plate also has at least one reference slit defined therein at a position radially of the circular row of the primary slits. A primary photoelectric detector including a source of light and a photo-sensor positioned one above the other with the circular row of the primary slits intervening therebetween is used to detect the passage of the primary slits therethrough while an auxiliary photoelectric detector including a source of light and a photo-sensor positioned one above the other with the path of travel of the reference slit intervening therebetween is used to detect the passage of the reference slit therethrough.

Abstract: The present invention provides a drive signal for a peristaltic pump motor. A first circuit is provided which generates a first series of pulses at a given frequency. A second circuit is provided which generates a second series of pulses having a frequency higher than the frequency of the first series of pulses. A third circuit is provided which generates a third series of pulses having a frequency between the frequency of the first and second series of pulses. Finally, a circuit is provided which combines the three series of pulses into a drive signal. The drive signal length is determined by the frequency of the first series of pulses. The drive signal further is divided into two sections, an initial pulse stage determined by the frequency of the third series of pulses, and a modulated pulse stage being a series of pulses determined by the frequency of the second series of pulses.

Abstract: An air detector according to the present invention utilizes a unitary type sensor for detecting air bubbles or columns in an infusion solution flowing through a tube. Because of a unique design for a tube-receiving groove and a cooperating abutting member, the difficulty in loading a tube heretofore encountered with the use of unitary type sensor is obviated. Thus, the tube can be loaded in the air detector easily with good reliability.

Abstract: A stepping motor driving apparatus includes a stepping motor and a pulse output circuit for outputting drive pulses for driving the stepping motor. A pulse generator generates further pulses which not only have frequency higher than that of the drive pulses but are capable of a variable duty factor at the frequency of the further pulses. A gate circuit receives the drive pulses from the pulse output circuit and the further pulses from the pulse generator so as to output the further pulses of the pulse generator during excitation of the drive pulses such that the stepping motor is driven by the further pulses outputted from the gate circuit.

Abstract: An encoder wheel (60) is provided for monitoring a peristaltic pump (20). The encoder wheel (60) provides a plurality of equispaced sectors (62) and a reference sector (66) provided at the outer radius of the encoder wheel (60). A vane slit (68) is provide radially offset from the sectors (62,66). A pair of optical couplers (72,74) are provided to read the sectors (62,66) and the vane slit (68).

Abstract: A modem for transmitting and receiving digital information includes an oscillator, a switch connected to both the oscillator and to a data input for switchably controlling the oscillator to impress data on a transmission channel, and a receiver also connected to the transmission channel for receiving data thereon to demodulate the data and supply it to a processor.

Abstract: A wireless superheterodyne receiver is provided having an antenna for receiving wireless transmissions, a preamplifier having an input connected to the antenna and an output, a crystal filter having an input connected to the output of the preamplifier and an output, a demodulator having an input connected to the output of the filter, the demodulator having a single mixer, an oscillator having a second crystal connected to the single mixer of the demodulator wherein the demodulator supplies at an output a demodulated signal based upon the wireless transmissions.

Abstract: Frequency modulation of an information signal is provided by applying the signal to series connected voltage variable capacity diodes. The reactance of the diodes is coupled through a transmission line to a cavity oscillator. The varying diode reactance causes a corresponding change in the frequency of modulation of the oscillator.The improvement comprises a linearization potentiometer which couples to the diodes and provides a means to vary the effective impedance presented to the cavity oscillator such that a linear change in signal voltage applied to the diodes results in a linear change of oscillator frequency.

Abstract: A modem for transmitting data over one frequency and receiving data over another frequency is disclosed having an oscillator for generating a first signal, a voltage controlled oscillator for generating a second signal, a mixer for mixing the first and second signals to provide a mixer output signal having the transmission frequency, an input data switch for modulating the mixer output signal in accordance with input data, a second mixer connected to the voltage controlled oscillator and to the received incoming signal and a receiver for demodulating the received signal data.