Abstract: A stepper motor control circuit reduces ripple current by applying both fast and slow current decays to a motor phase when current is being reduced in the motor phase while following a falling current waveform. The control circuit uses an initial fast decay to reduce a winding current and then switches to a slow decay until a winding current is sampled again. The control circuitry samples a winding current and compares the sampled current to a reference current to determine if current is to be applied or reduced using fast and/or slow decay methods. Different phase current sample circuits allow either constant current sensing or selective current sensing.

Abstract: A stepper motor control circuit reduces ripple current by applying both fast and slow current decays to a motor phase when current is being reduced in the motor phase while following a falling current waveform. The control circuit uses an initial fast decay to reduce a winding current and then switches to a slow decay until a winding current is sampled again. The control circuitry samples a winding current and compares the sampled current to a reference current to determine if current is to be applied or reduced using fast and/or slow decay methods. Different phase current sample circuits allow either constant current sensing or selective current sensing.

Abstract: A method for verifying that an assay methodology is properly performed, that assay reagents employed possess the necessary potency for accurately performing such assay methodology, and whether or not test samples or assay reagents have been tampered with or are adulterated, is described. The method is performed by employing an assay verification sample, comprising a positive analyte component and the test sample under analysis, wherein the assay verification sample is analyzed employing the same assay reagents and essentially the same assay methodology employed to analyze the test sample. The method is particularly useful for performing heterogeneous immunoassays on an automated continuous and random access analytical system.

Abstract: An automated liquid level sensing system for use in an automated, continuous, and random access analytical system is disclosed. A pipette probe is positioned above, and lowered into, a liquid sample container which contains the liquid to be detected. The probe is energized by a near radio-frequency (RF) signal source. A receiving antenna is positioned below the sample container, and is oriented so that very little signal is detected from the probe while the probe is in air. When the probe contacts liquid in the sample container, the electromagnetic field of the RF signal is increased and reoriented toward the receiving antenna. An autozero circuit maintains a near-zero output from the receiving antenna when slow changes in signal level occur due to changes in probe position or other environmental factors. The autozero circuit allows the sudden increase in signal amplitude, due to liquid contact, to pass to a receiver.

Abstract: A method and apparatus for washing clinical apparatus is disclosed. The apparatus is a device for washing clinical apparatus, wherein the clinical apparatus is employed, at different times, to contain a first test substance during a first testing step and a second test substance during a second testing step subsequent to the first testing step. The apparatus comprises a device for supplying a wash solution to the apparatus, and for varying the quantity of the wash solution supplied to the apparatus. The apparatus further comprises a control unit for controlling the device for varying quantity to vary the quantity of the wash solution in proportion to the potential for contamination between the first test substance and the second test substance contained in the apparatus.

Abstract: The present invention is a method for opening and closing a cap pivotally mounted on a container for storing reagents for use in an automated analytical instrument. The cap has one end for sealing the container and a tab extending from the other end for pivoting the cap. The method comprises the steps of positioning a closed container adjacent an actuating device mounted on the analytical system. The method further comprises the steps of projecting the actuating device against the top of the tab to pivotally open the cap to a position sufficiently vertical for aspirating reagent from the container, and retracting the actuating device from the cap to a position above the pivotal mounting thereof. The method comprises the final step of causing relative motion between the cap and the actuating device so that the actuating device drags along the top of the cap pivotally closing the cap to provide a sufficient seal on the container preventing evaporation of the reagent therefrom.

Abstract: A sample container segment assembly for use in an automated, continuous, and random access analytical system is disclosed. The assembly includes a sample container which is received by a sample container segment, and the sample container segment is received on a carousel of the automated analytical instrument. The test sample container includes an upper skirt and a body having a reservoir for receipt of the test sample. The segment includes a base, a frame, and a handle. The frame has a shelf for which the upper skirt of the test sample container rests on, and has openings for receipt of the body of the sample container. The carousel has a carousel trough for receipt of the base of the sample container segment, and has a plurality of alignment pins disposed in the carousel trough. The base of the sample container segment has a circular slot and an elongated slot for receiving the alignment pins and positioning the sample container segment relative to the carousel.

Abstract: A bubble flushing syringe for aspirating and dispensing fluids through an open-ended tip with precision and volumetric accuracy is disclosed. The syringe comprises a piston within a bore formed by a generally cylindrical wall having a closed end and an open end, wherein the piston forms an annulus with the wall and closed end of the bore, and is capable of reciprocating therein. The syringe further comprises an annular seal seated in the open end of the bore and circumventing the piston to close the annulus sufficiently snug to retain fluid when the piston reciprocates therethrough. An inlet for directing fluid to the annulus through the wall of the bore and an outlet for directing fluid from the annulus through the wall of the bore to the open-ended tip are positioned proximal to the annular seal and the line generally axially therebetween. A drive device is connected to the piston for reciprocating the piston within the bore.

Abstract: A magnetic ink character reading system is provided in which multi-element read heads are positioned in a spaced apart and staggered arrangement. Data signals occurring in the analog responses of the read heads are detected, and converted to discrete logic level signals under the control of a dynamically adjustable threshold. The logic level signals of each read head are sampled in response to independent data sample signals which are phase locked to the data rate of the respective read head. NRZ (non-return-to-zero) data signals formed thereby are synchronized to a common fixed frequency, and serialized faithfully to represent the characters appearing on documents passing the read heads.

Abstract: Printed bar codes which are either biphase modulated or bar-no-bar modulated are read as they pass an optical sensor. The video signal generated thereby is given a waveform having a constant reference level within an amplitude envelope of constant magnitude. The signal then is differentiated to provide a bipolar waveform having character dependent properties. The bipolar waveform is applied to a synchronizer to establish a digital synchronization waveform defining the time periods during which bar signals may occur. The bipolar waveform also is separated into positive and negative halves which are integrated separately and compared to a predetermined threshold to detect the presence of a bar. When a bar is present, the time of occurrence of the bar signal peak is correlated with the synchronization signal to identify either a logic one or a logic zero representation from the half-period position of the bar signal.