US4199265A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Motorless magnetically coupled stirrer
Assignee: Baxter Healthcare Corp
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Filing: 1978-10-30
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Granted: 1980-04-22
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Expires: 1998-10-30
Abstract
Abstract 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.
Inventors
- 👤 Robert A. Sanderson
- 👤 Patrick S. Chan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:15
CPC Classifications
H; H02; H02K; H02K37/00; H02K37/10; H02K37/12; H02K37/125; B; B01; B01F; B01F33/00; B01F33/45; B01F33/452; B01F35/00; B01F35/20; B01F35/21; H02K7/00; H02K7/14
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
74 words
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.
Claim 2
Dependent Claim
74 words
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.
Claim 3
Dependent Claim
66 words
The stirrer of claim 1 wherein said means for establishing a magnetic field comprises a plurality of coils positioned in a predetermined geometrical arrangement beneath said stir rod supporting surface, a plurality of pole pieces associated with each of said coils and extending in the predetermined arrangement toward said container, and means associated with each of said coils for completing a magnetic circuit between said coils.
Claim 4
Dependent Claim
49 words
The stirrer of claim 2 and means for applying said recurring pulses to adjacent ones of said coils in an overlapping pulse relationship whereby magnetic flux is built by an energization of each individual one of the coils before the magnetic flux built by its immediately neighboring coil disappears.
Claim 5
Dependent Claim
21 words
The stirrer of claim 2 and programmable means for controlling the generation and the application of said pulses to said coils.
Claim 6
Dependent Claim
25 words
The stirrer of claim 2 wherein said stir rod has an enlarged equatorial region forming a bearing surface on which said stir rod may turn.
Claim 7
Dependent Claim
25 words
The stirrer of claim 1 wherein said predetermined geometrical arrangement is a circle of pole pieces beneath said surface for creating a rotary magnetic field.
Claim 8
Dependent Claim
38 words
The stirrer of claim 1 wherein said predetermined geometrical arrangement is a row of pole pieces for creating a sweeping linear magnetic field for moving said stir rod in at least a linear motion along said linear field.
Claim 9
Independent Claim
105 words
A method for controlling the stirring of a fluid or similar mixable substance comprising the steps of: a. generating digitally controlled, recurring switching pulses for sequentially defining successive discrete time periods; b. generating successive magnetic fields responsive to said switching pulses, for sequentially stepping a magnetic field in a predetermined motion; c. positioning an integral non-magnetic container including the substance to be stirred within said stepping magnetic field; and d. positioning a magnetic stir rod which is entirely separate from said container in said container and within said stepping magnetic field, whereby said rod moves with said magnetic field in order to stir said substance.
Claim 10
Independent Claim
105 words
A method for controlling the stirring of a fluid or similar mixable substance comprising the steps of: a. generating digitally controlled, recurring switching pulses for sequentially defining successive discrete time periods; b. generating successive magnetic fields responsive to said switching pulses, for sequentially stepping a magnetic field in a predetermined motion; c. positioning an integral non-magnetic container including the substance to be stirred within said stepping magnetic field; and d. positioning a magnetic stir rod which is entirely separate from said container in said container and within said stepping magnetic field, whereby said rod moves with said magnetic field in order to stir said substance.
Claim 11
Dependent Claim
55 words
The method of claim 8 and an added step wherein said switching pulses of step a. are generated and applied under control of a programmable means, whereby said magnetic stir rod may be programmed to follow a great variety of different patterns of movement by generating and applying said switching pulses in a different order.
Claim 12
Dependent Claim
19 words
The method of claim 9 and the added step of generating and applying said switching pulses in overlapping relationships.
Claim 13
Dependent Claim
52 words
The method of claim 9 wherein said switching pulses are generated at a recurrence rate relative to the inertia of said stir rod which causes the switching pulses to lead the stir rod as it moves, so that said rod moves continuously and does not come to rest at any pole piece.
Claim 14
Dependent Claim
48 words
The method of claim 11 and the step of changing said recurrence rate with a ramp function whereby said pulses recur at an increasing or decreasing rate which varies as a function of the inertia of the stir rod so that it may accurately follow said magnetic field.
Claim 15
Dependent Claim
24 words
The method of claim 12 and the step of changing the direction of the magnetic field stepping each time that said recurrence rate slows.
Claim 16
Dependent Claim
146 words
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.
Claim 17
Dependent Claim
146 words
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.
Claim 18
Dependent Claim
26 words
The stirrer of claim 14 and means for varying said predetermined order to cause said rod to follow any of many alternative patterns of rod motions.
Claim 19
Dependent Claim
52 words
The stirrer of claim 14 wherein said digital means comprises two driver means, each of which controls the energizing sequence of one half of said coils, steering means for synchronizing said two drivers to energize said coils in either of two orders for driving said stir rod in either of two directions.
Claim 20
Dependent Claim
26 words
The stirrer of claim 16 and timer means for cyclically operating said steering means to sequentially reverse the directions in which said stir rod is driven.
Claim 21
Dependent Claim
74 words
The stirrer of claim 17 wherein said digital means also includes a pulse source having a variable pulse repetition rate, and means controlled by said timer for varying said variable repetition rate in a manner which speeds up the movement of said stir rod after each operation of said stir rod after each operation of said steering means and slows down said movement of said stir rod before each operation of said stir rod.
Claim 22
Dependent Claim
64 words
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.
Claim 23
Dependent Claim
64 words
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.
Claim 24
Dependent Claim
88 words
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.
Claim 25
Dependent Claim
88 words
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.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-22 | 1983-10-22 | 1984-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-22 | 1987-10-22 | 1988-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-22 | 1991-10-22 | 1992-04-22 | $7700.00 | Window Closed / Lapsed |