Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
Technical F'ield
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This invention relates to apparatus for
chemical -testing, and more specifically to an automatic
balancing mechanism for use with centrifuge apparatus
used in such chemical testing.
Background Art
In copending Canadian Patent Application
Serial Nos. 480,653, 480,654 and 480,657, filed
May 2, 1985, chemical testing appara-tus in -the form of
a centrifuge is disclosed. Such apparatus, as
described in such copending applications, the
disclosures of which are incorporated herein by
reference, is particularly suitable for use in carrying
out chemical testing procedures on various biological
fluids, such as blood, serum, urine, spinal and
amniotic fluids, and the like. As described in those
copending applications, the centrifuge apparatus
includes a plate member adapted to rotate at high
speeds about an axis on which there is mounted one or
more holding member(s) capable of receiving a sample
processor card which rotates with the plate member.
The holding member is adapted to receive a sample
processor card; the card defines a series of channels
and/or chambers through which liquid undergoing testing
can be moved under the influence of centrifugal force.
In the preferred embodiments of the
aforementioned centrifuge appara-tus, the holding member
is itself mounted for rotation relative to the plate
member so that -the direction of centrifugal force
exer-ted on the sample processor card can be changed to
control the flow of liquids therethrough, thereby to
effect transfer and ultimate mixing of liquids from one
chamber in the processor card to another.
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In the inventions described in the
aforementioned copending applications, the sample
processor card can be provided with a reagent ~or mixing
with, for example, a blood sample, and the mixing is
effected by means of centrifugal force. Accordingly,
when the disclosed chemical testing apparatu.s is in
operation, the centrifugal force can release the
reagent, separate solid part:iculate matter from the
fluid of the blood, measure both the reagent and the
blood fluid, mix them together, and finally, transport
them to a chamber from which the product of the chemical
testing can be measured, for example by optical means,
to determine the results of the test. Generally, such
results will be an indication of the presence or amount
of a particular analyte of interest in the sample.
In the preferred centrifugal apparatus
described in the foregoing copending applications, the
plate member is usually provided with two or more
holding members adapted to receive a sample processor
card. Since the position and weight of the holding
members with sample processor cards mounted thereon is
substantially the same, two sample processor cards can
be mounted symmetrically relative to the axis of
rotation of the plate member to balance the latter
during rotation. In some instances, however, the number
of sample processor cards which are physically
positioned in the holding members mounted on the
rotatable plate member do not distribute the weight
symmetrically relative to the axis of rotation, thereby
resulting in imbalance of the rotating plate member.
There is accordingly a need to provide means to
automatically balance the plate member so that, whether
a sample processor card is present in each holding
member or not, a substantially uniform balance in the
rotatable plate member is nonetheless achieved.
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SUMMARY OF THE_INV_ENTION
The concepts of the present invention reside in
apparatus for generating centrifugal forces, and
preferably include a plate member adapted to rotate at
high speeds about an axis on which there is mounted,
radially of the axis, a holcling means. ~he holding
means is mounted on the plate member ~or rotation
therewith, and, when the holcling means are more than one
in number, are preferably positioned symmetrically in
relation to the axis of rotation of the plate member.
As described in the foregoing copending
applications, the holding means is adapted to receive an
article to be subjected to centrifugal ~orce. The
article is, preferably, a sample processor card which
defines a series of channels and/or chambers through
which liquid undergoing testing can be moved under the
influence of centrifugal force.
The automatic balancing mechanism o~ the
present invention, which upon such centrifugal apparatus
as aforedescribed, includes at least one counterweight
means positioned on the plate member between the holding
means and the axis of rotation of the plate member.
Also positioned on the plate member is a trigger means
adjacent to the holding means and adapted to engage the
article to be subjected to centri~ugal force. Thus,
when such an article is positioned in the holding means,
the trigger means engages the counterweight means and
prevents displacement by centrifugal force of the
counterweight means. On the other hand, when no such
article is positioned in the holding means, the trigger
means does not enyage the counterweight means, and thus
centrifugal force, when the plate member is rotated
about its axis, displaces the counterweight means toward
the holding
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means, thereby to counterbalance the holding means not
containing the article.
It has been found, in accordance with preferred
embodiments of the invention, that a sample processor
card positioned in the holding means can be
counterbalanced by the counterweight means when no
corresponding sample processor card is positioned in an~
other holding means on the plate member. BecaUse this
automatic balancing feature is virtually self-activating
without the need for a separate actuation, apart from
positioning or not positioning a sample processor card
in the holding means, the user of the centrifugal
apparatus is assured that it will be balanced even when
it is used with an odd number of sample processor cards.
It is accordingly an object of the present
invention to provide an automatically-acting balance
mechanism for balancing centrifuges of the type afore-
described.
It is a more specific object of the inventlon
to provide such an automatic ba~ancing mechanism for
centrifuges in which that mechanism automatically
balances the rotating plate member of the centrifuge
when no sample processor card is present in a given
holding member.
These and other objects and attendant
advantages of the invention will appear more fully
hereinafter from the detailed description which
follows. For purposes of illustration, but not of
limitation, preferred embodiments of the invention are
shown and described with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF T~E DRAWINGS
Figure 1 is a top view in elevation of a
schematic diagram of centrifugal apparatus embodying the
automatic balancing concepts of the present invention;
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Figure 2 is a side-elevational view in
cross-section, and partially broken away to show details
of construction, of the apparatus shown in Figure 1,
taken generally along the line 2-2 thereof;
Figure 3 is a partially schematic view of a
portin of the apparatus shown in Figure 1, and showing a
portion o~ the centrifugal apparatus in an initial
operational (rotational) condition; and
Figure ~ is a view similar to Figure 3 but
showing the portion of the apparatus in a fully
rotational operational condition.
DETAILED DESCRIPTION OF THE_INVENTION
Referring now in more detail to the drawings,
Figures 1 and 2 illustrate preferred centrifugal
apparatus embodying the concepts of the invention. The
centrifuge generally shown includes a plate member 10
which is mounted for rotation about an axis 12. The
plate member 10 is preferably driven by a suitable drive
means 14, which may be, for example, an electric motor
operating at high speeds. While plate member 10 is
illustrated in FigUre 1 as a circular plate, it will be
understood that its configuration is not critical to the
practice of the invention. For example, it is equally
possible to employ a centrifugal arm mounted for
rotation about an axis.
Mounted on plate member 10 is at least one
sarnple processor card holding means 16 (although in the
preferred embodiment shown, two holding means 16 are
illustrated). The holding means 16 is adapted to
receive a sample processor card, as described more fully
in the foregoing copending applications~ As is
described in such copending applications, the card
holder 16 is preferably in the nature of a tray and is
rotatably mounted relative to the plate member 10 on an
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axis 18, specifically connected to mean.s 20 (Figure 2)
to rotate the card holder 16. Since the particular
means 20 to rotate the holding means 16 forms no part of
the present invention, the details thereof have been
omitted from the drawings for the sake of simplicity.
While the axis of rotation 12 of the plate
member 10 is illustrated in Figure 2 as being vertical,
it will be understood by those skilled in the art that
the orientation of the axis 12 is not critical to the
practice of the invention. Accordingly, the axis of
rotation of the plate member 10, while preferably
vertical, can also be horiæontal, or inclined in any
direction, since the effects of gravity on the sample
processor card rotating with the plate rnember 10 are
negligible.
In the preferred practice of the invent.ion, the
card holder 16 can be rotated or indexed relative to the
plate member 10 by the means 20. In an especially
preferred embodiment, the holding means 16 can be
rotated or indexed substantially 90 relative to the
plate member 10. However, as will be appreciated by
those skilled in the art, the holding means 16 can be
rotatable by an amount greater than 90, up to and
including a full 360. The important feature is that
the card holder 16 be adapted to receive the sample
processor card which is rotated relative to the plate
member 10 so that the direction of the centrifugal force
acting on the sample processor card can be altered to
effect the necessary fluid-transport functions during
the chemical testing operation.
For ease of description, shown in Figures 1 and
2 are a pair of holding means 16 mounted symmetrically
with respect to the axis of rotation 12 of the plate
member 10. As will be appreciated by those skilled in
the art, it is equally possible, and sometimes
preferred, to equip the plate member 10 with only one or
a greater number than two, of holding means 16 which can
be, and preferably are, symmetrically spaced about the
plate member 10.
The automatic balancing device of the present
invention includes a pair of counterweights 22 and 22'
which are capable of displacement along a radius of the
axis of rotation 12 of the plate member 10 toward and
away from the holding means :L6. Each of the
counterweights 22 and 22' is spring-biased by means of
spring means 24 and 24', whereby the counterweight can
be maintained in a stored position, illustrated by
reference to the counterweight 22' in Figure 1.
Positioned adjacent to the holding means 16 is
a trigger means 26, pivotally mounted about a pivot
point 28. The trigger means 26 has a portion 30 adapted
to engage a corresponding engagement means 32 of the
counterweight 22. The trigger means includes a cam
surface 34 which is adapted to engage a lateral surface
36 of a sample processor card 38, when the latter is
positioned in the holding means 16.
Considering the right-hand holding means 16 in
~igure 1, a sample processor card 38, placed in the
holding means 16, serves to pivot the trigger means 26'
against the effect of a spring 40', so that the engaging
portiGn 30' of the trigger means 26' engages the
corresponding engaging means 32' of the counterweight
22'. ~hus, as the plate member 10 is rotated, the
counterweight 22' is prevented, by the engagement of the
trigger means 26' with the counterweight 22', from being
displaced toward the holding means 16.
~ hen no sample processor card is positioned in
the holding means 16~ as shown in the left-hand side of
~igure 1, the trigger means 26 is biased by means of
spring 40 away from engagement with the counterweight
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means 22. Thus, as the plate member 10 is rotated, the
counterweight 22 is displaced against the action of the
spring 24 toward the left-hand holding means 16 shown in
Figure 1. The displacement of the counterweight 22 away
from the axis of rotation 12 of the plate member 10, as
is appreciated by those skilled in the art, serves to
counterbalance absence of the weight of the sample
processor card 38 in the left--hand holding means 16.
Thus, a sample processor card 38, by means of
the trigger means 26', causes the counterweight 22' to
remain in the stored position because of its presence,
while the absence of a sample processor card in the
left-hand holding means 16 allows the counterweight 22
to be displaced away from the axis of rotation 12 of the
plate member 10 to a balancing position, thereby to
offset and counterbalance the absence of the sample
processor card in the left-hand holding means 16 of
Figure 1.
It will be well understood by those skilled in
the art that other confiyurations and arrangements of
the counterweight with respect to the sample processor
card holding means are possible. For example, it is
possible to employ one counterbalance system for each of
a plurality of pairs of sample processor card holding
means 16 upon the plate member 10. In that way, a
sample processor card would always be provided to the
holding means 16 not equipped with the automatic
balancing device, while the opposite holding means 16
would be provided with an automatic balancing mechanism
to counterbalance the sample processor card when no
sample processor card is used in such opposite holding
means 16.
Referring now to Figures 3 and 4 of the
drawings for a further explanation of the operation of a
centrifuge incorporating the concepts of the present
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invention, in a preferred embodiment thereof, an
enlarged view o~ the counterweight 22 ~ t trigger means
261 and sample processor card 38 of Figures 1 and 2 is
shown. In operation of the centrifuge and concommitant
rotation of the plate member 10, as previously
described, initial engagement of the trigger means 26
with the counterweight 22~ is shown in Figure 3. In
such initial engagement, a gap 42 exists between an
upper edge 32a of the engagement means 321 of the
counterweight 22 ~; and portion 30' of the trigger means
261; the gap 42 is present at the beginning of rotation
of the plate member 10 when the centrifuge is initially
placed in operation, as is the case when/ for e~ample,
assays or chemical tests are being performed using the
centrifuge. At this point in operation, the trigger
means 261 is in contact with the card 38 along its cam
surface 341. However, as shown in ~igure 4~ as the
plate member 10 rotationally accelerates, the weight of
the counterweight 221 bearing against the trigger means
261 further rotates the latter so that the gap 42 closes
and the portion 301 of the trigger means 26~ contacts
the upper edge 32" of the engagement means 321 ~ The
trigger means 261 therefore is no longer in contact
along its cam surface 341 with the card 38. ThUS, the
card 38 can rotate freely relative to the plate member
10 without being hindered by the action of trigger means
261 ~
It will be understood that various changes and
modifications can be made in the specific details of
construction, procedure and use of the invention as
described herein, without departing from the spirit and
scope of the invention, which is defined solely in the
following claims.
