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US 4,199,265 AGranted
Motorless magnetically coupled stirrer
AssigneeAmerican Hospital Supply Corporation
InventorsRobert A. Sanderson, Patrick S. Chan
Life of this patent
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AssigneeAmerican Hospital Supply Corporation
InventorsRobert A. Sanderson, Patrick S. Chan
Estimating the term…
A plurality of magnetic field generating, electrical coils are preferably arranged in a circle, in one embodiment. Digitally controlled, recurring switching pulses are generated for sequentially defining a plurality of discrete time periods. During each of these time periods, a separate magnetic field is generated responsive to each switching pulse. The pulses are applied to the coil, in turn, for sequentially stepping a magnetic field in a rotary motion about the circle of coils. In other embodiments, the pole pieces may be arranged in another geometry. For example, they could be linearly positioned to slide a stirrer or to lift a stirrer member up a test tube. A substance which is to be stirred is placed in a non-magnetic container positioned within the stepping magnetic field. A stir rod of magnetic material is placed in the container and within the stepping magnetic field, so that the stir rod couples into and rotates or otherwise moves with the rotary magnetic field. The invention is particularly artractive when used with electronic controllers, such as counters, sequences, sensors, electronic controllers, or the like, since it is much easier for such a electronic devices to control digital pulses than to control analog currents.
A digitally controlled motorless stirrer comprising means for generating cyclically recurring pulses, electronically controlled means for establishing a stepping magnetic field responsive to said recurring pulses, a container, a magnetic stir rod positioned in said container and against a surface thereof made from a non-magnetic material, and means for supporting said surface of said container within said magnetic field in a position where said magnetic stir rod follows the stepping of said magnetic field.
A method for controlling the stirring of a fluid or similar mixable substance comprising the steps of:
An automatic stirrer comprising a circle of paired coils, each of said pair of coils being diametrically opposed in said circle, said coils being wound in directions to produce magnetically opposed flux fields, whereby one of said pair induces one magnetic pole when the opposite of said pair induces the opposite magnetic pole responsive to an energization of the pair of coils, digital means for sequentially generating switching pulses for energizing each of said pair of coils in a predetermined order around said circle, means for alternatively reversing the relative positions of said opposite magnetic poles when each of said pair of coils is energized, a free magnetic stir rod, means for supporting said stir rod in the magnetic fields created by said coils and means for varying the characteristics of said switching pulses to coordinate their generation with the inertia characteristics of said stir rod.
A stirrer comprising a plurality of linearly-oriented, magnetic pole pieces, digitally controlled means for sequentially energizing said pole pieces to create a linearly moving magnetic field, means for positioning a mixable substance in said field, and a magnetic stir rod positioned with said mixable substance for moving said mixable substance linearly as said stir rod moves back and forth past said linearly-oriented pole pieces.
A digitally controlled device comprising a plurality of electromagnetic means positioned to generate separate magnetic fields in a geometrical pattern, a magnetic stir rod, a non-magnetic surface positioned to support said stir rod under gravity adjacent said plurality of magnetic means with an orientation wherein said pattern of magnetic fields coincides with said surface, and digital control means for selectively and individually energizing said electromagnetic means to step said fields in said pattern whereby said stir rod moves in the pattern established by the stepping of said field.
Dependencies are inferred from the claim text.