U.S. patent number 3,863,426 [Application Number 05/364,064] was granted by the patent office on 1975-02-04 for disc transfer devices to petri dishes.
This patent grant is currently assigned to Agence Nationale de Valorisation de la Recherche. Invention is credited to Patrice Marie Denis Paul Courvalin.
United States Patent |
3,863,426 |
Courvalin |
February 4, 1975 |
DISC TRANSFER DEVICES TO PETRI DISHES
Abstract
A disc transfer device for loading a Petri dish. The transfer
device includes a plurality of storage tubes with stacks of discs
of blotting paper which are, for example, impregnated with an
antibiotic to be evaluated. A transfer plate displaces the discs at
the bottom of their respective stacks to ejection locations in
alignment with ejection passageways which have diameters slightly
less than that of the discs thereby preventing the free fall of the
discs onto the gelose medium. A control shaft is rotatable for
displacing the transfer plate from its disc receiving position to
its ejection position and slidably movable perpendicular to the
receiving surface for descending plungers which drive the discs to
the receiving surface. All the discs are brought into contact with
the germ seeded gelose medium in the Petri dish with exactly the
same contact pressure, reproductible from cycle to cycle, this
pressure being determined by the mass of the plungers. The Petri
box is provided with various indicia including intersecting
perpendicular lines on its outer bottom wall for aiding the
determination of the germ inhibiting zone measured by the discs in
position at the intersections.
Inventors: |
Courvalin; Patrice Marie Denis
Paul (Paris, FR) |
Assignee: |
Agence Nationale de Valorisation de
la Recherche (Neuilly-sur-Seine, (Hauts-de-Seine),
FR)
|
Family
ID: |
9099166 |
Appl.
No.: |
05/364,064 |
Filed: |
May 25, 1973 |
Foreign Application Priority Data
|
|
|
|
|
May 26, 1972 [FR] |
|
|
72.018905 |
|
Current U.S.
Class: |
53/237; 53/390;
221/270; 53/247; 221/93 |
Current CPC
Class: |
C12M
99/00 (20130101) |
Current International
Class: |
C12M
1/16 (20060101); C12M 1/20 (20060101); B65b
005/06 (); B65b 067/02 () |
Field of
Search: |
;53/166,235,237,247,254,390
;221/93,124,132,224,225,232,233,270 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Spruill; Robert L.
Attorney, Agent or Firm: Diller, Brown, Ramik &
Wight
Claims
I claim:
1. A transfer device for depositing discs on a receiving surface,
comprising a casing having a bottom particularly adapted to face
the receiving surface, a plurality of tubes mounted in the casing
for storing stacks of discs, an ejection passageway in said casing
laterally adjacent each stack, transfer means for transferring the
disc at the bottom of each stack laterally to an ejection position
in alignment with a corresponding one of said ejection passageways,
a plurality of plungers arranged in alignment with said ejection
passageways for sliding movement perpendicular to the bottom of the
casing towards the receiving surface for driving the discs from
their ejection position through said passageways onto the receiving
surface and single control means for sequentially actuating said
transfer means and said plunger.
2. A transfer device according to claim 1, together with a platen
carrying said plungers for simultaneous movement, and means
individually mounting each plunger on said platen for freedom of
movement relative to said platen in a direction away from the
bottom of the casing wherein the weight of each plunger defines the
pressure with which each disc is applied against the receiving
surface.
3. A transfer device according to claim 1, wherein the cross
section of the ejection passageways is smaller than the cross
section of the discs for which said tubes are intended to hold so
as to prevent the free fall of the intended discs from their
ejection position to the receiving surface.
4. A transfer device according to claim 3, wherein the largest
lateral dimension of the intended discs exceeds the largest lateral
dimension of the ejection passageways by 0.05 mm.
5. A transfer device according to claim 1, wherein the bottom of
the casing is adapted to cooperate with the side wall of a Petri
dish to accurately position said ejection passageways relative to
the Petri dish, the bottom wall of the Petri dish constituting the
said receiving surface.
6. A transfer device according to claim 5, further comprising a
network of perpendicular lines parallel to the walls of the dish
and equidistant from one another, the intersections of said
perpendicular lines defining the centers of both said ejection
passageways and the points of application of the discs on the
receiving surface.
7. A transfer device according to claim 1, wherein said single
control means includes a platen supporting all of said plungers for
simultaneous movement and a control shaft, means mounting said
control shaft for rotational movement relative to said platen and
for conjoint axial movement with said platen.
8. A transfer device according to claim 7, wherein the rotational
movement of the control shaft effects the displacement of the
transfer means between its disc receiving position and the ejection
position; and wherein the conjoint sliding movement of the control
shaft effects in the downward direction the driving of the discs
into contact with the receiving surface.
9. A transfer device according to claim 8, wherein means are
provided to prevent the conjoint sliding movement of the platen
with the control shaft until the control shaft has been rotated to
bring the discs to their ejection position.
10. A transfer device according to claim 8, wherein the transfer
means comprises a transfer plate, and further comprising
retractable abutment means associated with the transfer plate for
preventing its return to its disc receiving position until the
discs brought to their ejection position are driven to the
receiving surface.
11. A transfer device for depositing discs on a receiving surface,
comprising a casing having a bottom particularly adapted to face
the receiving surface, a plurality of tubes mounted in the casing
for storing stacks of discs, an ejection passageway in said casing
laterally adjacent each stack, transfer means for transferring the
disc at the bottom of each stack laterally to an ejection position
in alignment with a corresponding one of said ejection passageways,
a plurality of plungers arranged in alignment with said ejection
passageways for sliding movement perpendicular to the bottom of the
casing towards the receiving surface for driving the discs from
their ejection position through said passageways onto the receiving
surface, each plunger including a rod for sliding movement in its
associated ejection passageway and a head, a platen including a
plurality of cylinders defined therein, and each plunger head being
mounted for sliding movement in an associated cylinder which
determines the path of movement of the plunger.
12. A transfer device according to claim 11, further comprising a
control shaft, said control shaft being mounted for rotational
movement relative to the platen and conjoint axial movement with
said platen.
13. A transfer device according to claim 12, wherein the rotational
movement of the control shaft effects the displacement of the
transfer means between its disc receiving position and the ejection
position; and wherein the conjoint sliding movement of the control
shaft effects in the downward direction the driving of the discs
into contact with the receiving surface.
14. A transfer device according to claim 13, wherein means are
provided to prevent the conjoint sliding movement of the platen
with the control shaft until the control shaft has been rotated to
bring the discs to their ejection position.
15. A transfer device according to claim 13, wherein the transfer
means comprises a transfer plate, and further comprising
retractable abutment means associated with the transfer plate for
preventing its return to its disc receiving position until the
discs brought to their ejection position are driven to the
receiving surface.
Description
The present invention relates to an improved device for the
transfer of flat objects such as discs to a receiving surface. For
the sake of clarity and simplicity the flat articles which are to
be transferred to the receiving surface, as will be described
below, are uniformly designated as discs; it is obvious, however,
that this term is not intended as a limitation as to their
configuration or shape.
This type of transfer device is employed for the simultaneous
positioning of discs impregnated with different substances,
antibiotics for example, for qualitative evaluation according to a
particular characteristic; in the case of antibiotics, this is
their activity with respect to a certain germ (micro-organism). The
qualitative evaluation is produced in the form of an antibiogram
which is a visual representation of antibiotic activity.
In order to construct such an antibiogram, the surface of a thin
layer of a sterile gelose medium is seeded with the germ being
studied; after suitable drying, the discs formed of blotting paper
about 6 mm in diameter and about 0.8 mm in thickness, and
previously impregnated with different antibiotics being evaluated,
are regularly distributed over the surface of the seeded gelose
medium. The combination is then maintained in an incubator for 18
hours at approximately 37.degree.C in order to enable the
multiplication of the germ and the diffusion of the antibiotic
through the medium. The reading of the antibiogram consists of
measuring the diameter of the germ growth inhibiting zone centered
on the disc. The discs, commonly less than 20 in number, are
deposited individually by means of tweezers or simultaneously by
means of an automatic transfer device.
The automatic transfer devices commonly used generally comprise
several storage tubes each containing a stack of discs previously
impregnated with a particular antibiotic. The maneuvering of
ejection means enables the simultaneous discharge of a disc from
each one of the storage tubes dropping them to the surface of the
medium through a guide channel. These transfer devices are easy to
operate but nevertheless have the disadvantage of not being able to
assure a satisfactory contact of the discs on the medium which may
cause the displacement of the disc in the course of subsequent
handling, or an irregular or partial distribution of the
antibiotic. In order to remedy the situation, the operator is
obligated to carefully press each disc down so as to obtain
intimate contact between the disc and the medium. It frequently
occurs that the disc turns during its fall which complicates
subsequent identification in the case of discs printed on only one
face. It even happens that the disc rolls along the surface of the
medium discharging part of its contents which invalidates the
results of the antibiogram.
An aim of the invention consists in overcoming the drawbacks as
well as the errors and loss of time in prior automatic transfer
devices.
One aspect of the invention consists in a transfer device for
depositing discs on the receiving surface of a Petri dish,
comprising a casing with its bottom facing the receiving surface, a
plurality of tubes mounted in the casing for storing stacks of
discs, transfer means for transferring the disc at the bottom of
each stack to an ejection position in alignment with a
corresponding plurality of ejection passageways, a plurality of
plungers arranged in alignment with said ejection passageways for
sliding movement perpendicular to the bottom of the casing towards
the receiving surface for driving the discs from their ejection
position through said passageways onto the receiving surface.
Preferably, the plungers have a predetermined weight defining the
pressure of application of the discs on the receiving surface.
Preferably, the cross section of the ejection passageways is
slightly smaller than the cross section of the discs thereby
preventing the free fall of the discs to the receiving surface
without the force exerted by the plungers.
Preferably, the transfer device has a control shaft rotatably
mounted for transferring the disc to the ejection position and
slidably mounted for driving the discs to the receiving
surface.
Advantageously, the bottom of the casing is adapted to cooperate
with the side walls of the Petri dish, the said receiving surface
being the bottom wall of the Petri dish.
The Petri dish is preferably of square shape and the bottom of the
Petri dish has a network of spaced perpendicular lines parallel to
the sides of the dish, the points of intersection of the lines
defining points of application of the discs.
A principal advantage of the present transfer device is that drives
the discs to the receiving surface with a precise, reproducible
force assuring the desired contact between the disc and the
receiving surface.
In the preferred field of application in combination with a Petri
dish, the present transfer device drives the discs through the
passageways onto the gelose medium depositing the discs thereon
with a precise predetermined, reproducible force assuring the
desired contact between the disc and the gelose medium.
Further features and advantages of the transfer device and Petri
dish according to the present invention will be brought out in the
description which follows with reference to the accompanying
drawings, in which:
FIG. 1 is a plan view of the base of the transfer device showing
the mounting of the system of storage tubes and associated ejection
passageways;
FIG. 2 is a sectional view taken along the line II--II in FIG.
1;
FIG. 3 is a sectional view taken along the line III--III in FIG.
1;
FIG. 4 is a sectional view similar to FIG. 2 with the control knob
in its upper position after being turned through 90.degree. ;
FIG. 5 is a sectional view similar to FIG. 4 in which the control
knob is brought into position by downward displacement after
rotation;
FIGS. 6 and 7 are details in perspective on an enlarged scale,
partly in section of a storage tube and an associated ejecting
means which is shown in two different positions; and
FIGS. 8-11 show a preferred embodiment illustrating the Petri dish
adapted to be associated with the transfer device shown in FIGS.
1-7 and its cover .
Reference will now be made to FIGS. 1-3 in which a transfer device
designated generally by the reference numeral 1 is shown in
position on a Petri dish 2, the bottom of the Petri dish being
covered with a layer of gelose medium providing a receiving surface
3. The transfer device 1 essentially comprises a casing 4 receiving
the disc storage tubes 5, a platen 6 carrying push members or
plungers 7 as well as a control shaft 8 with a knob 9 at its outer
end. The casing 4 comprises a body 10 with a base 11 and a cover
12. The outwardly projecting portions 13 on the base 11 rest
against the sides of the Petri dish so that the lower face 14 of
the base is at a predetermined distance from the gelose layer on
the plate or receiving surface 3.
A series of cylindrical recesses 16 receive the lower ends of the
storage tubes 5 and a series of bores 15 which form ejection
passageways for depositing the discs on the receiving surface 3 are
provided in the base 11.
In the illustrated embodiment the platen 6 comprises upper and
lower plates 17 and 18 between which the flange 19 of the spindle 8
is held. The platen 6 is thereby secured to the spindle 8 for
vertical displacement therewith. Heads of the plungers 7 are in
rubbing contact and slidable along cylinders 21 formed in the
platen 6, the cylinders 21 being slightly longer in axial
dimensions than the heads 20.
The bottom of each of the storage tubes 5 keyed in an associated
recess 16 is formed as a dimetral stirruplike member having
transverse slots 23 (FIGS. 6 and 7) defining openings adapted to
the dimensions of the discs being handled.
The upper end of each storage tube 5 is provided with resilient
means (not illustrated) acting against the stack of discs for
assuring the regular descent thereof according to the transfer
cycle. The storage tubes 5 pass freely through the bores in the
platen 6 and the cover 12 and are held in position by a
horizontally displaceable locking plate 24 for the storage tubes
responsive to a vertical force acting against the top portion of
symmetrically oriented radial projections 25 arranged at a suitable
position along the storage tubes 5. A pair of push buttons 26 and
27 each projecting from one side of the casing 4 permit the locking
and unlocking of the storage tubes 5.
The transfer plate 28 is linearly slidably mounted on the base 11
of the casing and has a series of apertures 29 (FIGS. 6 and 7) each
defining a transfer tongue 30 flanked by slots 31 providing passage
to the bottom of the storage tube. The leading edge 32 of the
tongue 30 shaped to conform to the shape of the disc, is
illustrated in its rearaward position in FIG. 4, i.e., in
horizontal and vertical alignment with the disc being transferred;
and in its forward position in FIG. 7, the disc 33 having been
displaced, as will be explained below, is in vertical alignment
with the associated ejection passageway 15.
The displacement of the transfer plate 28 is controlled by the
control spindle 8 in the following manner: a pivot 34 coaxial with
the control spindle 8 and received in the base (FIGS. 1 and 2) has
at its upper end pulley 35 with a lateral tab 36. A blind axial
socket 37 of square cross section in the illustrated embodiment of
FIG. 1 is arranged in the pulley 34. The lower end of a rod 38 also
of a square cross section is received in the socket 37. Moreover,
one end of a traction cord 40 is secured to the slide 39 coupled to
the plate 28 at one side of the plate perpendicular to the
direction of displacement. The other end of the cord is partly
wound around the pulley 35 and connected to the tab 36. Clockwise
rotation of the rod 38 therefore effects the displacement of the
slide 39 and the transfer plate 28 in the direction of the arrow
(FIG. 2).
The abutting of the slide 39 with the end of its housing precisely
limits the path of movement of the transfer plate 28 which at the
end of the cycle is returned to the starting position by return
springs 41 schematically represented in FIG. 1.
Once the linear transfer movement of the transfer plate 28 has been
inititated by the rotation of the pulley 35, retractable abutment
means 42 shown in FIGS. 2, 4 and 5, comprising a leaf spring 43
inserted at one end in a swinging lever 44 while the other end of
the leaf spring cooperates with a stop 45 on a slide 46 connected
for movement with the plate 28, prevents the rearward movement of
the plate 28 by the springs 41. At the end of the transfer cycle,
the return of the slide 46 effects the resetting of the leaf spring
43.
The control spindle 8 has a tubular body 47 slidably and pivotally
mounted in a sleeve 48, the lower end of the sleeve being secured
to the cover 12. The body 47 ends with the flanged socket portion
49 which as described above is held in a cylindrical bore 50 in the
platen 6. The mounting couples the platen 6 and the body 47 for
up-and-down reciprocating movement but enables the free rotation of
the socket 49 in the bore 50 and therefore the body 47. This socket
49 has a square interior cross section adapted to receive in
rubbing contact for sliding movement the free end of the rod 38
coupled at its lower end to the pulley.
A guide plate 51 overlying the transfer plate 28 is provided for
guiding the lower end of the plungers 7. The guide plate 51 has a
plurality of bores 52 arranged along the axes of the ejection
passageways 15 as well as for freely receiving the bases of the
disc storage tubes 5.
The platen 6 is held in its upper position by springs 53 (FIGS. 1
and 3) guided in the tubular members 54 resting on the guide plate
51 and inserted at their upper ends in the cover 12. T-shaped keys
55 are held captive in the plate 6, the cross bars thereof
extending into the apertures in the tubular members 54, said
T-shaped keys providing a bearing surface for the upper ends of the
springs 53.
As it will be described hereinafter, the operation of the transfer
device comprises sequentially rotational then sliding linear
displacement of the control spindle 8. For this purpose, the
control knob 8 is provided with a vertically depending finger or
key 56 (FIG. 4), the sleeve 47 having an opening 57 (FIG. 2) in
which the finger or key 56 can be received.
Interlocking means, not illustrated in detail in the drawings,
controls the control spindle 8 depending on the position of the
locking plate 24 so that all rotational or sliding movement of the
control spindle 8 is prevented when the locking plate 24 is not in
its locked position.
The operation of the device as described above will now be
described:
The storage tubes 5, once filled, are secured in position by the
locking plate 24; the finger or key 56 rests on the sleeve 48 at a
predetermined angular distance from the opening 57. The platen 6 is
maintained in its upper position by the springs 54 whereas the
transfer plate 28 is held in its rearward position by the springs
41. The head of each plunger rests on the bottom of its associated
cylinder 21, the bottom of the push members or plungers being in
engagement with the associated bore in the guide plate 51.
In the first phase of operation, the operator turns the control
knob 9 in the clockwise direction (arrow G in FIG. 1); the cord 40
pulls the slide 39 in the direction of the arrow F and each of the
tongues of the transfer plate 28 engage a disc at the bottom of a
stack in a corresponding storage tube 5 to transfer the said disc
to an associated ejection passageway 16 (FIGS. 6 and 7).
During the initial phase of operation, the retractable abutment
means 42 protrudes to prevent the return of the transfer plate 28
until it has completed the movement of the discs to their ejection
position and the discs arrive on the receiving surface.
When the discs come into forward abutment against the slide 39
(FIG. 4), they are in vertical alignment with the ejection
passageways 16, the finger or key 56 on the control knob 8 being in
alignment with the opening 57.
At a second phase of the operation, the operator exerts a force
downwardly against the control knob 8 which brings about the
descent of the platen 6 and the plungers 7. After passing through
the guide plate 51, the plungers come into contact with the
transferred discs and drive them down through the ejection
passageways 16. The bores of these passageways are machined to a
dimension slightly less than the disc diameter, for example 0.05
mm, so that only the positiive action of the plungers 7 is able to
bring about the descent of the discs to the receiving surface. When
the platen 6 arrives at its lowermost position (FIG. 5), the
ejected discs emerge from the passageways 16 with the ends of the
plunger 7. As it was noted above, the cylinders 21 with which the
heads are in slight frictional sliding contact have an axial
dimension slightly greater than that of the heads. From this fact
it follows that the heads 20 which were in contact with the upper
ends of the cylinders 21 continue there descending path of movement
by gravity until they come to abut against the lower end of the
cylinders. Consequently, the plungers 7 descend with the ejected
discs and their free fall is calculated so that the discs are
applied against the receiving surface 3 supporting the gelose
medium by a force determined by the mass of the plunger which may
therefore be precisely reproduced in another transfer device.
Once the downwardly directed force exerted by the operator is
released, the springs 53 return the platen and the knob 6 upwardly;
as soon as the key or finger 56 is out of engagement with the
opening 57 the springs 41 act to return the transfer plate 28 to
its rearward position while the control knob 8 undergoes a
counterclockwise rotational movement returning it to the position
shown in FIG. 2. The device 42 is reset during the return path of
movement of the transfer plate; the transfer device is then ready
for another transfer cycle.
Reference will now be made to FIGS. 8-11 showing an alternative
embodiment of the Petri dish (FIGS. 8 and 9) whose receiving
surface is adapted to receive the discs deposited thereon by the
present transfer device. The cover therefor is shown in FIGS. 10
and 11.
The dish generally designated by the reference numeral 60 has a
flat bottom wall 61 and upstanding side walls 62 connected by
fillets 63. Supporting feet 64 are arranged at the corners of the
dish 60.
A network of perpendicular straight lines equidistant from one
another and parallel to the sides of the dish are provided on the
exterior face of the bottom wall 61. The intersections of the
perpendicular straight lines define points of application for the
centers of the discs. The straight lines may be shaped as ribs
formed during the molding of the dish or etched grooves.
Graduated scales are provided at 66 and 67 centered at points of
intersection of the straight lines which may be millimetric or
other suitable scales, such as concentrations expressed in
micrograms per milliliter. These inidicia or scales may be etched
into the bottom wall 61 or simply secured thereto by any suitable
means, for example printed sheets readable through the transparent
gelose medium and bottom wall.
The bottom wall could of course be provided with other indicia as a
function of the measurements to be effectuated.
The cover 68 (FIGS. 9 and 10) is adapted to be received on the dish
60 and comprises a top wall 69 and a skirt which is fitted onto the
side walls of the dish. Bosses 71 formed on the interior face of
the top wall 69 prevent the top wall from resting directly on the
edge of the side walls. In this way the interior of the dish 60
with its cover 68 is aerated thereby avoiding the formation of
condensation along the interior face of the top wall of the cover
which might interfere with readings.
The cover 68 has a rim 72 adapted to receive the support feet of
the dish 60 for stacking the dishes with their covers on top of one
another.
The problems solved relative to the particular application
concerned by an aspect of the invention include:
a. the determination of the minimum inhibiting concentrations of
the germs relative to various antimicrobic agents (by the technique
of diffusion in a jellied medium with the aid of correlating
curves); and
b. the clinical categorization of the results.
The advantages of the transfer device in combination with the Petri
dish as described above include:
1. automatic operation of the device whereby it is no longer
necessary to actually push each disc into the gelose medium;
2. the discs being put in contact with the gelose medium with the
same reproducible pressure, the pressure exerted by each plunger
being the same and constant from cycle to cycle (the intimate
contact of the discs with the surface of the gelose medium assures
excellent diffusion of the antibiotic therein);
3. the increase of the effective surface of the gelose medium owing
to the particular arrangement of the discs;
4. reduction in the number of errors; and
5. the qualitative and quantitative reading of the results being
more precise, rapid and easy since the 16 discs positioned at the
intersection of the network of perpendicular lines associated with
graduations marked on the outer face of the bottom of the box
enable an immediate and precise reading of the "diameter" of
inhibitor zone along each of two perpendicular axes.
It is preferable to deliver the dishes with the gelose medium
therein (the thickness of the medium being about 4 mm), the
variations of the diameter of the inhibitor zones due to the
differences in the thickness of the gelose medium can be thereby
avoided.
It is also possible to eliminate overlapping of the inhibitor zones
(the overlapping creating qualitative reading errors) on the
condition that the diameter of the zones does not exceed 30 mm
which is generally not the case.
The present invention is of course not limited to the illustrated
and described embodiment but, on the contrary, includes all
alternatives and modifications within the scope of the appending
claims.
* * * * *