Weighing scales – Combined
Patent
1993-04-01
1994-12-06
Miller, Jr., George H.
Weighing scales
Combined
177118, 128DIG13, G01G 1952, G01G 1302
Patent
active
053713290
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a device for simultaneous weighing and agitation.
The technical sector of the invention is the field of constructing an electronic precision balance.
One of the main applications of the invention is making weighing or balancing devices that simultaneously agitate the balance tray that receives the element to be weighed, which element may be a bag for collecting blood. Other applications can also be envisaged in industrial fields that also require a substance to be weighed with fairly high accuracy while maintaining a degree of agitation so as to mix the substance with another during weighing, as may occur in the manufacture of perfumes, of medicines, of paints, . . .
In the field of withdrawing blood, equipment already exists enabling blood to be withdrawn while satisfying standards laid down by the authorities, which in France means a maximum of 7 ml/kg of donor weight and a maximum take of 450 ml. In addition, the blood withdrawn must be mixed with an anticoagulant which is already contained in the collection bag.
For the purpose of assisting operators in collecting blood in compliance with these standards, and thus while monitoring as accurately as possible the quantity taken from a donor, patent applications have been made for various devices, for example:
Patent application No. 2 514 893 filed Oct. 19, 1981 by MCB: that application describes a method and a device for programmable weighing of a mixture in suspension having one of its constituents being added progressively thereto, with the constituents being agitated periodically; it is used in particular for mixing blood that is withdrawn progressively from a donor with an anticoagulant. The characteristic of that apparatus is that after each period of agitation, inflow of the external constituent is interrupted during each weighing operation and the apparatus includes means for stopping the alternating operations of inflow agitation and of weighing once a weighing operation indicates that a certain predetermined weight has been reached.
French patent application 2 548 135 filed May 19, 1983 by Vibration Internationale SARL describes an installation for filling flexible containers on balance pans with accompanying vibration. Those installations do not relate to the field of withdrawing blood and they are applicable to containers in the form of cylindrical bags having respective filling valves. The system described includes a frame that vibrates during said filling, and between two filling sequences, the frame is placed on a weighing platform situated therebeneath by vertical displacement of the container on said weighing tray.
The drawbacks of the two above systems are essentially that the weight of the liquid inserted into the bag or the container is not measured continuously, so good measurement accuracy is not possible since accuracy may drift between two readings, and secondly since agitation is also interrupted while the measurement is being performed, it is not possible to guarantee that the substance is homogeneous, and when the substance is blood that can be a major therapeutic drawback. This latter criterion also applies to patent application No. 2 603 190 to Centre Regional de Transfusion Sanguine, filed by Mr. MASSE et al., on Aug. 29, 1986 and relating to a method and apparatus for quantitative monitoring of withdrawal and also to a method and an installation for withdrawing blood from a donor for treatment purposes: the apparatus comprises a stand, a container support, and means for measuring a parameter related to the quantity withdrawn, and various other additional means. The applicant specifically claims the fact that the support is stationary and that there is no substantial agitation of the blood in the container: in the present invention that is considered as being a major drawback, as mentioned above.
To satisfy this object of simultaneous weighing and agitation, various other patent applications are also known:
Patent application No. 2 574 540 filed on Dec. 10, 1984 by Mr. BRUNET, and
REFERENCES:
patent: 3557789 (1971-01-01), Poitras
patent: 3698494 (1972-10-01), Gaudin
patent: 3924700 (1975-12-01), Lindsey et al.
patent: 4027735 (1977-06-01), Floyd
Hemopharm Service
Miller Jr. George H.
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