An electronically controlled intravenous infusion set of the gravity feed type having a flow path including a drip chamber and an internal valve for regulating flow through the set. Electromagnetic valve operating structure, positioned outside the IV set, controls the internal valve in response to an electronic control system. The electronic control system serves to open the valve to allow a drop to fall, and includes a control circuit. The control circuit includes an optical drop detector, associated with but positioned outside the drip chamber, which senses the falling drop and signals the control circuit to close the valve. The control circuit also includes a variable frequency clock and associated digital selectors for affording an attendant the ability to precisely select a desired drip rate. An alarm system, operating on digital principles, senses high drop rate or low drop rate conditions and, in response thereto, puts the control system into an alarm condition. The alarm system includes means for digitally adjusting the sensitivity thereof to provide high sensitivity at low drip rates but to decrease the sensitivity at higher rates so that premature alarm conditions are avoided.

Electronically controlled intravenous infusion set

A Hall-effect control apparatus incorporating an actuator member having a magnetic core, and which is pivotally mounted on a base for movement in X-axis and Y-axis directions. An electrically energized coil excited with a. c. voltage produces a fluctuating magnetic field in the vicinity of the core. Four Hall-effect sensors are mounted on the base, and are arranged to sense changes in the a. c. field as the core member moves. The output of the Hall-effect sensors is both d. c. and a. c.; an electrical circuit connected therewith processes these voltages so as to cancel out any d. c. components thereof. The output of the electrical circuit in turn provides two voltages which are indicative of the X-axis and the Y-axis positions of the actuator member. The device is immune to interruption arising from d. c. fields, such as that of the earth; also significant immunity against error due to temperature fluctuations is realizeable, as is immunity to error arising from aging of the various components. There is thus achieved improved accuracy and linearity as compared to the various devices of the prior art.

Hall-effect controller

A system (10) for optimizing the gain of an avalanche photodiode (12) and an associated avalanche photodiode preamplifier (14) includes a variable voltage power supply (58) interconnected to the avalanche photodiode (12) for providing a bias voltage source for the avalanche photodiode (12). Circuitry (26, 28) is provided for measuring the output noise level of the avalanche photodiode (12) and preamplifier (14). Additional circuitry (46, 48) is responsive to the circuitry (26, 28) for measuring the output noise level of the avalance photodiode preamplifier (14) for generating a control signal. The control signal is applied to the variable voltage power supply (58) for varying the bias voltage applied to the avalanche photodiode (12) by the variable voltage power supply (58) to control the output noise level of the avalanche photodiode (12), such that the output noise level of the avalanche photodiode (12) matches the output noise level of the avalanche photodiode preamplifier (14) to thereby optimize the operation of the avalanche photodiode ( 12) and the avalanche photodiode preamplifier (14) combination.

Avalanche photodiode gain control system

A light source in an optical character recognition system is automatically controlled to operate at a plurality of light intensities. A relatively high light intensity is used to illuminate an object bearing indicia to be read. A relatively low light intensity is used at all other times. A plurality of detectors sense reflected or ambient light and produce output signals indicative of the intensity of the reflected or ambient light. First and second signals are generated to indicate whether the detector output is greater than or less than a predetermined threshold. The number of first and second signals generated in response to the outputs of the detectors are summed separately. If the number of first signals equals or exceeds a first predetermined number, the object is illuminated at a high light intensity. If the number of first signals is less than the first predetermined number, or if the number of second signals generated equals or exceeds a second predetermined number, the light source is switched to a low level light intensity.

Method and apparatus for illuminating an object bearing indicia

A drive apparatus, in particular for the automatic actuation of a sliding door of a motor vehicle, comprising a fast running motor, the motor shaft of which is connected to a transmission with a large step-down ratio, the transmission having a first gear wheel which can be secured against rotation, via a releasable blocking device, and a second rotatable gear wheel which is rotationally fixedly connected to an output drive shaft and which is rotatable relative to the first gear wheel by the rotation of the motor when the first gear wheel is blocked, with the number of teeth of the first gear wheel only differing by a few teeth from the number of teeth of the second gear wheel and with the large step-down ratio being determined by this difference of the tooth numbers. By releasing the blocking device, the step-down ratio of the transmission changes. In particular a step-down ratio of 1:1 results. The transmission is thereby capable of being driven in reverse, so that a manual actuation of the sliding door of a motor vehicle is possible, without the requirement for a releasable clutch device between the sliding door and the drive apparatus.

Drive apparatus in particular for a sliding door of a motor vehicle

An optical positive feedback sensor circuit which converts regularly coded information into electrical signals. When not obstructed by the coded opaque pattern on a moving information carrier light from a light emitting diode is detected by a phototransistor. The output of the phototransistor is then amplified. A portion of the amplifier output provides positive feedback through the light emitting diode, driving the circuit into saturation. A circuit is included to maintain a light level at least sufficient to restart the operation after a period of light obstruction.

Lyman F Van Buskirk

Papers

Optical positive feedback sensor circuit

Self-contained servomechanism