Abstract: Optical components and methods for an I.V. flow detector providing complete coverage of a drip chamber through the use of a single emitter and receiver. The optical components take the light of a single emitter and spread it uniformly across the entire drip chamber. Furthermore, the light is collimated as it passes through the chamber. In addition, the optics collimates the light at some point in its path from the emitter to the drip chamber. Similarly, it collimates the beam of radiation at some point in its path from the drip chamber to the receiver. Further, the optics creates a plane of symmetry for the light path passing through the center of the drip chamber and lies perpendicular to the path of the light. The design specifically takes into account the optical characteristics of the drip chamber itself.

Abstract: A drop detector for intravenous systems in which an infrared emitter is pulsed at 10 kHz. The pulsed radiation passes through a drip chamber and then to a detector. The detector circuit determines the amplitude modulation of the 10 kHz. carrier frequency. This provides an indication of when the drop falling through the drip chamber has interrupted the light beam. An automatic gain control circuit maintains the output of the detector, on a long time constant basis, at a constant level to eliminate the vagaries of drip chambers with different optical characteristics and the like. When the AGC circuit lacks the ability to maintain the output of the detector circuitry at a constant level, a fault detector provides an alarm to indicate that the circuitry has exceeded its operational range.

Abstract: An adjustable clutch mechanism for fixing the relative position of two objects rotationally coupled relative to each other. The pressure resisting the change of rotational position submits to adjustment to permit facile movement but yet resists change from the selected position. The mechanism finds particular utility for holding a portable computer terminal's cover containing a display at a desired position relative to the base containing the keys. The clutch mechanism itself includes two sets of annular rings held against each other by a nut and bolt pressing against a spring which in turn presses against one of the rings. Tightening the screw applies greater pressure to the rings and prevents the relative rotation. The first set of the rings moves with the cover while the second set of rings has a fixed rotational orientation relative to the base. A tubular shaft, affixed to the base, passes through the center of the rings engaging tabs of the second set.