Chemical analyzer

• US 5,336,467 A
• Filed: 07/02/1993
• Issued: 08/09/1994
• Est. Priority Date: 11/22/1989
• Status: Expired due to Fees

• Current Assignee: Vettest SA
• Original Assignee: Vettest SA
• Inventors: Clampitt, Roger, Heidt, Thomas, Will, Henry, Rhodes, Greydon, Plasensia, Armand
• Primary Examiner(s): Housel, James C.
• Assistant Examiner(s): Pyon, Harold Y.
• Application Number:
  US08/087,180
• Time in Patent Office: 403 Days
• Field of Search: 422/64, 422/63, 422/82.05, 422/100, 436/46, 436/54, 73/1 H, 73/863.01, 73/864.18, 222/390, 425/145, 364/167, 364/555
• US Class Current: 422/64
• CPC Class Codes: G01N 2035/00049 for loading/unloading a carousel
• CPC Class Codes: G01N 2035/00079 Evaporation covers for slides
• CPC Class Codes: G01N 2035/00237 Handling microquantities of analyte, e.g. microvalves, capillary networks
• CPC Class Codes: G01N 2035/00376 Conductive heating, e.g. heated plates
• CPC Class Codes: G01N 2035/00752 bar codes
• CPC Class Codes: G01N 2035/1034 Transferring microquantities of liquid
• CPC Class Codes: G01N 35/00029 provided with flat sample substrates, e.g. slides G01N35/028 takes precedence
• CPC Class Codes: G01N 35/00594 Quality control, including calibration or testing of components of the analyser
• CPC Class Codes: G01N 35/00712 Automatic status testing, e.g. at start-up or periodic
• CPC Class Codes: G01N 35/025 having a carousel or turntable for reaction cells or cuvettes
• CPC Class Codes: G01N 35/10 Devices for transferring samples or any liquids to, in, or from, the analysis apparatus, e.g. suction devices, injection devices G01N35/0099 takes precedence
• CPC Class Codes: G01N 35/1004 Cleaning sample transfer devices
• CPC Class Codes: Y10T 436/112499 with sample on test slide
• CPC Class Codes: Y10T 436/119163 with aspirator of claimed structure

Abstract

A chemical analyzer includes a transport mechanism having a rotatable turntable adapted to hold a plurality of reagent test slides, a sample metering device, an incubator or temperature controller, a reflectometer and associated electronics and software. The rotatable turntable preferably holds up to twelve slides about its circumference, which slides are loaded onto the turntable by an inserter mechanism. The turntable positions the reagent test slides under the metering device, which device deposits a predetermined amount of sample onto each slide. The turntable also carries the slides above a reflectometer. After testing has been completed, an ejector mechanism automatically removes the reagent slides from the turntable.

Claims

1. A method of compensating for the backlash between a lead screw and a lead screw engaging member of a fluid sample metering device, the lead screw engaging member moving reciprocatingly in the axial direction of the lead screw upon rotation of the lead screw, which method comprises the steps of:

measuring the axial distance the lead screw engaging member moves in a first axial direction to a first position when the lead screw is rotated in a first rotational direction a predetermined number of revolutions;

measuring the axial distance the lead screw engaging member moves in a second axial direction which is opposite to the first axial direction from the first position when the lead screw is rotated the predetermined number of revolutions in a second rotational direction which is opposite to the first rotational direction;

determining the difference in the distances which the lead screw engaging member moved in the opposite first and second axial directions;

storing a value corresponding to the difference in distance in a storage memory;

sensing whenever the lead screw is to change direction of rotation from the first rotational direction to the second-rotational direction; and

adding a rotational amount corresponding to the difference value to the number of rotations the lead screw is turned in the second rotational direction to compensate for the backlash between the lead screw and the lead screw engaging member.