U.S. patent number 3,857,485 [Application Number 05/259,767] was granted by the patent office on 1974-12-31 for flexible containers for liquid sample spectrometry and methods and apparatus for forming, filling and handling the same.
This patent grant is currently assigned to Packard Instrument Company, Inc.. Invention is credited to Edmund Frank.
United States Patent |
3,857,485 |
Frank |
December 31, 1974 |
FLEXIBLE CONTAINERS FOR LIQUID SAMPLE SPECTROMETRY AND METHODS AND
APPARATUS FOR FORMING, FILLING AND HANDLING THE SAME
Abstract
Flexible sample containers for liquid scintillation spectrometry
analysis of test samples containing one or more radioactive
isotopes disposed in a liquid scintillator wherein the flexible
sample containers either in individual or strip form are made of
layered, flexible, light-transmissive, polyester film and are
provided further with means for avoiding light "piping" or optical
isolation from respective adjacent sample containers. Apparatus for
handling such flexible sample containers is provided with light
transmission sealing means for preventing entry of ambient light or
escape of light from the photomultiplier tube detection devices.
Also disclosed are methods and apparatus for filling, forming,
sealing and handling the aforementioned flexible sample containers
that readily lends itself to fully automated production line type
operations.
Inventors: |
Frank; Edmund (Chicago,
IL) |
Assignee: |
Packard Instrument Company,
Inc. (Downers Grove, IL)
|
Family
ID: |
22986287 |
Appl.
No.: |
05/259,767 |
Filed: |
June 5, 1972 |
Current U.S.
Class: |
206/216;
250/432R; 53/453; 206/524.2; 356/246; 383/63; 24/30.5S; 206/463;
383/78 |
Current CPC
Class: |
B65D
81/30 (20130101); G01T 1/2047 (20130101); G01T
7/08 (20130101); G01N 2021/0364 (20130101); Y10T
24/155 (20150115) |
Current International
Class: |
B65D
81/30 (20060101); G01T 7/00 (20060101); G01T
1/00 (20060101); G01T 1/204 (20060101); G01T
7/08 (20060101); B65d 065/16 (); G21f 005/00 () |
Field of
Search: |
;206/84,56AB,56AA,46P,46PU,46M,45.34,78B ;229/65 ;53/29
;250/16SC |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dixson, Jr.; William T.
Attorney, Agent or Firm: Wolfe, Hubbard, Leydig, Voit &
Osann, Ltd.
Claims
I claim as my invention:
1. In a sample container for liquid scintillation spectrometry
analysis including at least a pair of layers of flexible,
light-transmissive, polyester film,
means defining a joint between said layers to form an enclosed bag
portion for holding said liquid sample,
means for filling said bag portion,
the filling means being sealable when the bag portion is filled
with sample to form the liquid tight seal with said sample within
the container bag portion, the improvement comprising,
annular light reflective means disposed about the periphery of said
bag portion and the central portion of said bag remaining
light-transmissive.
2. A flexible sample container as claimed in claim 1 wherein said
light reflective means is disposed on both sides of the bag
portion.
3. A flexible sample container as claimed in claim 1 wherein said
light reflective means is an aluminized film member secured to said
bag portion.
4. A flexible container as claimed in claim 1 wherein said
reflective means comprises an opaque white film member secured to
said bag portion.
Description
DESCRIPTION OF THE INVENTION
This invention relates generally to flexible sample containers and
apparatus for filling, forming and handling the same in liquid
scintillation spectral analysis of test samples containing one or
more radioactive isotopes disposed in a liquid scintillator. More
particularly, the invention relates to improved flexible sample
containers and filling, forming and handling arrangements for such
flexible sample containers in individual or strip form and which
readily lend themselves to fully automatic operations.
BACKGROUND AND OBJECTS
Flexible sample containers for liquid scintillation spectral
analysis of test samples containing one or more radioactive
isotopes disposed in a liquid scintillator and methods and
apparatus for handling the same are described and claimed in the
copending application of Lyle E. Packard and Ariel G. Schrodt, Ser.
No. 192,543 filed Oct. 2, 1971 and assigned to the assignee of the
present invention. Such flexible containers comprise a flexible bag
formed in layered polyester films which are heat sealed, welded or
otherwise joined to define a closed flask between the layers. The
aforesaid copending application of L. E. Packard et al. further
describes and claims methods and apparatus for utilizing such
flexible containers for liquid scintillation detection operations
in a wholly automated manner.
It is therefore, the general object of this invention to provide
improved flexible sample containers and mechanisms for filling and
handling such containers for spectral analysis of test samples
confined therein, characterized in that such containers and
mechanisms are relatively simple and low in cost of production, yet
maintain the high degree of counting efficiency required in liquid
scintillation spectrometry. Another objective of the invention is
the provision of flexible containers which may be produced in a
continuous strip wherein barriers are provided between individual
sample holding portions of the strip to prevent light piping
between samples during counting.
A more specific object of the invention is to provide procedures
and apparatus for filling and sealing flexible sample containers
which are characterized by their simplicity and reliability and
wherein the filling and sealing may be done in a rapid
production-like manner.
It is still a further object of the invention to provide low cost
flexible sample containers that may be produced as a continuous
strip, yet separated into individual containers for storage and
handling with sample changing and counting apparatus. In this
connection, it is a related object of the invention to provide
improved apparatus for spectral analysis of test samples in
flexible sample containers of the foregoing type.
DESCRIPTION OF DRAWINGS
Other objects and advantages of the invention will become apparent
as the following description proceeds, taken in conjunction with
the accompanying drawings, in which:
FIG. 1 is a front sectional view of an exemplary radioactive sample
handling and measuring apparatus, housed in a suitable cabinet and
depicting the handling of flexible containers in accordance with
the present invention;
FIG. 2 is an enlarged fragmentary view taken of the counting
station of the apparatus in FIG. 1 illustrating light piping
prevention means in the form of annular seals associated with the
photomultiplier tubes and here showing the tubes brought into
contact with the container in the counting station;
FIG. 3 is a diagrammatic illustration of an exemplary arrangement
for preparation of a continuous strip of flexible sample
containers;
FIG. 4 is an enlarged perspective view of a portion of a strip of
containers shown in FIG. 3, here depicting one form of light piping
prevention barrier between the container portions of the strip;
FIG. 5 is an enlarged, fragmentary top plan view of the flexible
containers of FIG. 4;
FIG. 6 is a perspective view showing a portion of a strip of
another form of flexible containers;
FIG. 7 is a view taken along the line 7--7 in FIG. 6;
FIG. 8 is a diagrammatic illustration of an arrangement for
producing the flexible containers of FIGS. 6 and 7;
FIG. 9 is a view in perpective of yet another strip form of
flexible containers;
FIG. 10 is a front plan view of still another strip form of
flexible containers;
FIG. 11 is a view in perspective of yet another strip form of
flexible containers adapted to be closed with closed clips;
FIG. 12 is a transverse sectional view taken along the line 12--12
in FIG. 11 and here depicting a crimp clip in sealing position;
FIG. 13 is a view in perspective of another strip form of flexible
containers having a clip for sealing;
FIG. 14 is an enlarged fragmentary sectional view of a container of
FIG. 13 sealed with a clip;
FIG. 15 is a view in perspective of an individual flexible sample
container shown in a rigid mount and depicting the folding that
takes place to complete the mount;
FIG. 16 is an exploded view in perspective of an individual form of
flexible container and reflection rings provided therefor;
FIG. 17 is a view of the container FIG. 16 with the rings in
place;
FIG. 18 is a fragmentary diagrammatic view showing the flexible
sample containers of FIGS. 16 and 17 disposed between a pair of
photomultiplier tubes;
FIG. 19 is a view in perspective of yet another form of flexible
container construction having rigid support means integrally formed
therewith;
FIG. 20 is an exploded view of the components of the flexible
container of FIG. 19;
FIG. 21 is an edge view of the flexible container of FIG. 19;
FIG. 22 is a perspective view of yet another form of flexible
container with rigid support disposed between a pair of sheets;
FIG. 23 is an exploded view of the container of FIG. 22;
FIG. 24 is a view taken along the line 24--24 in FIG. 22;
FIG. 25 is a diagrammatic view illustrating the process sequence of
making, filling and stacking individual flexible containers
embodying features of the present invention;
FIG. 26 is a fragmentary view of the filling station of FIG. 23,
here depicting the injection means for inserting samples into the
container;
FIG. 27 is a diagrammatic representation of an alternative form of
detector apparatus adapted to handle individual flexible sample
containers;
FIG. 28 is a view in perspective of a detector module, showing the
shutter operating mechanism and sample container elevator;
FIG. 29 is an enlarged fragmentary view, partly in section showing
the details of an axially shiftable photomultiplier tube
mounting;
FIGS. 30, 31 and 32 are diagrammatic representations, respectively,
of a cycle of operation of the shutters and elevator for an
exemplary detection apparatus; and
FIGS. 33 and 34 are alternative arrangements for shuttering
containers into a counting station while sealing against entry of
ambient light.
While the invention is susceptible of various modifications and
alternative forms, specific embodiments thereof have been shown by
way of examples in the drawings and will herein be described in
detail. It should be understood, however, that it is not intended
to limit the invention to the particular forms disclosed, but, on
the contrary, the intention is to cover all modifications,
equivalents and alternatives falling within the spirit and scope of
the invention as expressed in the appended claims.
GENERAL APPARATUS ARRANGEMENT
Referring to FIG. 1, there is illustrated a liquid scintillation
apparatus, indicated generally at 40, which houses a scintillation
detector mechanism or apparatus 42. The detection apparatus of FIG.
1 is detailed in the aforementioned copending application of Lyle
E. Packard and Ariel G. Schrodt, Ser. No. 192,543 filed Oct. 2,
1971. In brief, the detection apparatus 42 as viewed in FIG. 1,
includes a base assembly 44 which houses a pair of photomultipliers
PMT No. 1, PMT No. 2 disposed on opposite sides of a counting
station 46.
The photomultipliers PMT No. 1, PMT No. 2 are preferably mounted so
as to permit controlled simultaneous movement toward and away from
the counting station 46. To this end, in the present exemplary
arrangement the photomultiplier tubes are slidably carried in
tubular guides 48 with ball bearing mounts 50. Light-tight bellows
52 interconnect the guides 48 with the photomultiplier tube sockets
54. The bellows contain compression springs 56 to normally bias the
tubes outwardly from the counting station 46.
In order to effect the controlled simultaneous movement of the
photomultiplier moves toward one another along a common axis, there
is provided a pair of cams 58, 60 acting respectively upon the
sockets 54 of photomultiplier tubes PMT No. 1 and PMT No. 2. A
suitable actuating mechanism (not shown) rotates the cams 58,60 to
act upon the sockets and drive the photomultiplier tubes toward
each other which, as more fully discussed below, permits close
optical coupling with sample containers in the counting station
46.
FLEXIBLE CONTAINER ARRANGEMENT
As shown in conjunction with FIG. 1, the sample containers utilized
with the apparatus 40 are in the form of a continuous strip 62 of
flexible bags 64. For details of the flexible sample container
construction, reference is made to the aforementioned copending L.
E. Packard et al. application Ser. No. 192,543. For the purposes of
this application it should suffice to say that the flexible sample
containers 64 are produced from layered light-transmissive
polyester film strips which are heat sealed, welded or otherwise
suitably joined to define a closed flask-like portion between the
layers. The flask-like portion has provision for injecting test
samples into the closed chamber therein and is sealable to confine
the sample in the bag portion without leakage.
In its preferred form, the bag is circular in the plane of the
layers with a diameter closely approximating the diameters of the
photomultiplier tubes so that there is comformity with the round
photomultiplier tubes to provide the optimum counting geometry for
the container structure.
FLEXIBLE CONTAINER TRANSFERENCE AND HANDLING
With the provision of a continuous strip of flexible containers,
compact storage on a reel 66 (FIG. 1) is possible and the
transference of the sample through the detector apparatus involves
a passing of the strip from reel 66 to reel 68, the latter being
shown as manually operated through crank handle 70. During the time
when the containers are being shifted into and out from the
counting station 46, the photomultiplier tubes PMT No. 1 and PMT
No. 2 are in the retracted, axially spaced apart position. When the
particular container 64 holding the test sample to be analyzed is
in the counting station, the photomultiplier tubes are then moved
axially together until they are in intimate contact with the outer
faces of the container (FIG. 2).
The photomultiplier tubes are brought together with sufficient
pressure so as to "squeeze" the flexible container therebetween
causing the outer walls of the container to conform with the faces
of the photomultiplier tubes. With this arrangement, an extremely
close optical coupling results which minimizes lost light at the
contact surfaces of the container and tubes and high quantitative
accuracy of liquid scintillation counting results.
OPTICAL ISOLATION
In accordance with one of the aspects of the present invention,
provision is made in respect of the apparatus and the flexible
sample container bags or both to avoid light "piping" (transmission
of light through the film material) and to provide optical
isolation from sample containers adjacent to the containers in the
counting station. To this end, the photomultiplier tube guides 48
are provided with flanged ended portions 72 to which there is
mounted soft annular sealing rings 74 which coaxially contact
opposite sides of the interconnecting strips or borders between the
container bags. The sealing rings exclude outside light from
entering the detector counting station when the tubes are in the
axially together position as shown in FIG. 2, in addition to
confining light generated with the photomultiplier tubes from
passing through the film layers themselves into the sample storage
enclosures on either side of the counting station.
Elimination or reduction to tolerable minimums of light "piping"
through the interconnecting strip material of the containers is
accomplished by the provision of light piping prevention means
formed on the container strip web or border which may act in
cooperation with the soft sealing rings. To this end, referring to
FIGS. 4 and 5, conjointly, there is illustrated one form of light
piping prevention means which comprises an embossed area 76 on web
62 between respective adjacent sample containers 64.
The embossment 76, whqch may be achieved by conventional embossing
rolls or dies provides a zig-zag, non-planar path that prevents
light from being transmitted directly through the web into adjacent
sample containers by portions of the continuous strip. The soft
annular sealing rings, discussed above, in connection with the
photomultiplier tube sleeves will conform themselves with the
raised and indented portions of the embossments to provide a more
effective seal against entry or loss of light.
a. Fabrication of bi-layered Containers
In order to generate a continuous strip of sample containers of the
type described above, a system such as that illustrated in FIG. 3
may be utilized. The arrangement is such that a pair of rolls 78 of
wound polyester film strip supply the strips as they are unwound.
The strips 80,81 are flattened against each other as they pass
through gathering rolls 82,83 before passing into the heat sealing
and embossing apparatus 84.
The exemplary heat sealing and embossing apparatus 84 is shown in
the form of a pair of cooperating heated dies 85, 86, the latter of
which is shiftable by a servo mechanism 87 or the like to clamp the
film strip layers between the dies for simultaneously effecting the
heat sealing and embossing operations. Controlled intermittent
movement of the film strips and actuation of the heat sealing
apparatus produces a plurality of the flask-shaped containers 64
separated by embossments 76 and the strip of containers is then
wound into a roll 88 for compact storage in readiness to be filled
with test samples.
b. Multi-layered Containers
Referring now to FIG. 6, there is shown a slightly modified form of
flexible container arrangement for handling liquid samples for
scintillation spectrometry wherein instead of two film layers being
provided, the container strip is formed from three layers. The
layers include a pair of outer transparent or light transmissive
layers 90,91 bonded or sealed to an inner opaque layer 92 (FIG. 7).
The flask or bag portion 91 defining the sample containers is
formed from a cut-out in the central opaque strip such as that
defined by the centrally disposed circular cut-out 95 and the
filling opening cut-out 94.
The surface area of the outer strips surrounding the defined
container portions 91 being heat sealed or bonded to the inner
opaque strip are left with a roughened surface 96 which renders
them opaque to prevent light piping between the sample container
bag through interconnecting material of the strip.
c. Fabrication of Multi-layered Containers
Referring to FIG. 8, there is shown exemplary forming system
arrangement for producing the continuous flexible container strip
of FIGS. 6 and 7. As shown in FIG. 8, the opaque strip 92 is moved
intermittently along a straight path from a source (not shown) to a
take up shaft 93. During its movement, the strip 92 first passes
through a punch 98 which cuts out the key-hole shaped opening 100
at predetermined spaced intervals along the strip. Next, the strip
92 is sandwiched between strips 90,91 supplied from rolls 101,102,
respectively prior to passing between gathering rollers 104. The
tri-layered strip after emergence from the gathering rolls passes
through a sealing and cutting apparatus 105 which joins the outer
strips 90,91 to the opaque strip 92 and trims the top border
leaving a neck-like opening in the flasks.
d. Alternative Optical Isolation Arrangements
Turning now to FIG. 9, there is illustrated another form of light
transmission or light piping prevention means for the flexible
sample container arrangements similar to those shown in FIG. 4 and
FIG. 6. In the present instance, the sample containers are again in
the form of flexible bags made up of layered, light-transmissive
polyester film joined to define closed flasks between the layers.
The top and bottom borders 109, 110 are opaque through the
provision of embossments, metallized strips, or magnetizable strips
such as that described in copending application Ser. No.
192,543.
In order to prevent light transmission through the layered film
borders on opposite sides of the sample bag portion, elongated
transverse slots 112 are formed in the layered borders adjacent to
the bags 108. The slots 112 provide discontinuities in the path of
light travel through the film layers.
A still further modification is illustrated in FIG. 10 where
instead of one slot, there is provided a plurality of rows of
spaced slots 114. The slots of each row are staggered with respect
to the slots of an adjacent row or rows so that a straight path of
travel for light is avoided. The slots also add more flexibility to
the strip for handling and storage in a rolled form.
e. Container Sealing
Referring now to FIG. 11, there is illustrated a portion of a
continuous strip of flexible sample containers 116 having a
plurality of flask-shaped bag portions 118 therein and provided
with neck filling openings 120. After the bag portions have been
filled with the test samples, the neck portions may be heat sealed
or otherwise joined to provide a liquid tight seal against escape
of the test samples. However, in FIGS. 11 and 12 there is shown an
alternative arrangement for sealing the containers which provides
an effective seal yet allows the containers to be easily unsealed
for removal of the samples therefrom.
To this end, the edge portion 122 of the strip containing the necks
120 is folded over and a crimp clip 124 is clamped over the folded
portion overlying the container filling neck. The clip 124 may be
made of any suitable material such as a soft metal which is
sufficiently ductile to tightly clamp the bent over film portions
of the container with crimping operations or the like.
Referring to FIGS. 13 and 14, conjointly, there is illustrated
another form of removable clip adapted to seal the filling neck
portion of flexible sample containers such as those indicated at
126 in FIG. 13. In the present instance, portions of the film
border material intermediate that containing the neck portions 128
of the containers 126 have been cut away, as indicated generally at
130, so that the neck portions 128 project outwardly from the top
edge 132 of the container strip. The clip 134 is formed of a
resilient material such as plastic and has a generally U-shape with
a corresponding protuberance 136 and socket 138 on the inside of
the leg portions thereof. The arrangement is such that when the
clip is placed over the protruding meck portion 128 and the
protuberance 136 is snapped into the socket 138 it tightly clamps
the container neck portion 128 between the protuberance and socket
to prevent escape of the liquid sample in the container bag
portion.
f. Mounted Flexible Sample Container
It will be appreciated that the flexible sample containers as
discussed above may be handled individually as well as on a
continuous strip. Thus, in accordance with another aspect of the
present invention, provision may be made for mounting an individual
flexible sample container in a rigid frame which offers yet another
mode of storing, handling and transporting the containers. In the
exemplary arrangement shown in FIG. 15, an individual flexible
container 140 is sandwiched between a pair of rigid layers 142, 143
that may be made of a single piece of stock folded over such as
indicated at 142'. The rigid material may be polyethylene coated
cardboard or the like with cut-out openings 144 (only one being
shown) to permit the bag portion 140 to protrude through the
opening after assembly.
g. Increased Light Collecting Efficiency
In carrying out another aspect of the present invention provision
may be made with respect to the flexible container bag portions for
further increasing the light collecting efficiency with the use of
the containers. In carrying out this aspect of the invention,
annular members 146, 147 or the like of light reflective material
are placed about the peripheries of the bag portions 148 (FIGS. 16
and 17). The annular members may be any suitable light reflective
material such as aluminized film or opaque white film. In the
alternative it will be appreciated that instead of using separate
members a reflective coating may be applied about the periphery of
the bag portion so that the reflective surface is formed in
situ.
Referring to FIG. 18, it will be seen that when the sample
container of FIG. 17 is disposed between a pair of photomultiplier
tubes PMT No. 1, PMT No. 2 the tube faces engage the outer surfaces
of the container bag portion and the peripheral portions thereof
containing the light reflective members 146 cover the sides of the
bag and provide sloped reflective surfaces which serve to reflect
light emitted by the photomultiplier tubes back into the liquid
sample rather than allowing it to pass out through the side wall of
the container.
h. Formed Containers
In the prior described flexible container arrangements, the bag
portion which holds the liquid sample was simply defined by a
joining or sealing of the layered polyester film leaving the
enclosed flask-like chamber between the layers for holding the
sample. Ordinarily, this arrangement provides a sufficient volume
for liquid test sammples according to the area between the joint
formed in the layers. Where it is desired to have a sample
container which will carry a still larger volume of test sample but
without increasing the lateral dimension of the bag portion, and in
accordance with still another aspect of the present invention, the
flask portion may be bulge formed in the direction perpendicular to
one or both of the film layers.
As illustrated in FIG. 19, sample container 150 includes polyester
film layers 151,152 and a rigid mount layer 153. A portion of the
flask 154 and filling neck 155 are bulge formed in the layer 151
(FIG. 20) and the rigid layer 153 is provided wiith an opening 158
to permit protrusion of the bulged portion 156 of layer 152
therethrough (FIG. 21).
Referring to FIGS. 22,23, and 24, conjointly, there is shown
another form of molded flexible container arrangement 160 wherein
outer layers 161,162 include bulged flask portions 163 and an
intermediate rigid layer 164 is sandwiched between inner and outer
layers 161,162. The rigid layer 164 disposed between the film
layers is provided with a cut-out 165 corresponding in shape to the
flask-shaped bulged portions 163 of the outer layer.
FORMING, FILLING AND HANDLING INDIVIDUAL FLEXIBLE SAMPLE
CONTAINERS
Turning now to FIG. 25, there is illustrated an exemplary system
for forming, filling and arranging individual flexible sample
containers in a continuous production-like manner. In the system, a
pair of polyester film strips supplied from respective sources (not
shown) are merged together through the nip of gathering rolls 172
and then passed through a heat sealing forming station and which
effects the formation of the flask-like containers 178 in the
strip. The forming unit 174, for example, includes vacuum forming
dies 175,176 that bulge the container walls outwardly at the same
time that the heat seal joint is formed. The layered strip moves
intermittently so that each of the operations takes place while the
strip is at rest.
After formation, the containers 178 are advanced to a filling
station 180 wherein liquid sample from a source 181 is injected
into the container with a hollow needle 182. As best shown in FIG.
26, the needle 182 is adapted to penetrate the neck portion of the
container 178 and inject the liquid sample through a hollow opening
183. In order to permit air inside the container 178 to escape
during filling, the needle is provided with a vent including an
opening 184 disposed longitudinally within the needle and an
interconnecting transverse outlet port 185 which permits the
escaping air to pass to the atmosphere.
In the production line filling station, a pair of reciprocatingly
actuated plungers 186,187 are provided on opposite sides of the
container strip and arranged to apply a pressure to the container
faces that stiffens the flask portions to allow for penetration of
the needle.
Following the filling operation, the filled containers advance to a
heat sealing station wherein a heat sealing head 188 transversely
oriented with respect to the neck of the flask shaped container
seals the neck as indicated at 190 beneath the opening left by the
filling needle.
The filled, sealed, sample containers are then moved to a pressure
test station 192 wherein a predetermined compressive pressure load
is applied to test for leakage and the ability to withstand
pressures which correspond substantially to that of the load
applied by the photomultiplier tubes when they compress the flask
during counting.
The container strip then moves to a cutting station 194 wherein a
cutter 196 severs the layered film between filled flasks to form
individual containers 198 which are then placed in proper order in
a compartmentalized holding tray 200 or the like.
Turning to FIG. 27, there is illustrated diagrammatically a liquid
scintillation apparatus, indicated generally at 202, which may be
utilized for spectral analysis of the test samples stored in
containers 198 held within tray 200. The detection apparatus 202,
as that described in connection with FIG. 1 above, includes a pair
of axially shiftable photomultiplier tubes PMT No. 1, PMT No. 2
disposed on opposite sides of a counting station 204 within a light
tight housing 205 (shown in phantom). The loaded tray 200 is
inserted within a sealed sample source supply chamber 206 adjacent
the input side of the detector and a sealed sample receiving
chamber 207 attached to the housing 205 adjacent the output side of
the detector holds a tray 208 which is initially empty and receives
the sample containers after testing.
The trays 200 and 208 are mounted so as to move transversely with
respect to the axis of the detector counting station so that the
supply tray 200 places the sample containers in position for
transference to the counting station and the receiving tray 208
provides an empty space for receipt of the sample container which
has been tested.
Instead of passing the sample containers from a tray in the source
chamber completely through the detector apparatus to the receiving
tray, provision may be made for transferring containers
individually to the counting station and returning the container
after counting to the tray from which it came. Referring to FIG.
28, there is shown an exemplary detector counting station and
transfer arrangement with photomultiplier tubes mounted for axial
shifting toward and away from the counting station similar to that
described in connection with FIG. 1. For convenience, the
corresponding components previously described in connection with
FIG. 1 have been indicated by the same reference numerals followed
by the letter "A."
In order to shift the photomultiplier detection device axially
toward the counting station, cams 58A, 60A are driven by their
respective shafts 210, 211 and geared to 212,213 through drive
shaft 214 carrying gears 215,216 from a motor 218.
A rectangular box-like housing transversely disposed between the
photomultiplier tube guides 48A and secured thereto define the
counting station. As best shown by references to FIGS. 28,29, and
30, conjointly, the housing 220 has side openings 222 to permit
entry of the photomultiplier tubes, a top opening 224 for entry of
the sample container 225 and a bottom opening 226 coupled to a tube
or sleeve 227 through which an elevator shaft 228 passes. For
details of an elevator operating arrangement and control therefor,
reference is made to L. E. Packard U.S. Pat. No. 3,188,468 issued
June 8, 1965.
Pursuant to the invention, the counting station housing 220 is
provided with a shutter arrangement to permit entry of a sample
container while excluding light from the photomultiplier tubes and
after the sample has entered the counting station to close off the
top opening to exclude ambient light, and then open the side
openings permitting entry of the photomultiplier tubes into the
counting station.
To this end, a slidable sample entry opening shutter 230 is
positioned beneath the sample entry opening 224 and a pair of
shutters 232,233 are positioned adjacent the photomultiplier tube
entry openings 222. The entry opening and tube opening shutters are
alternately shifted between their open and closed positions by
means of a pin and slot leakage arrangement, indicated generally at
234 (FIG. 29). The pin 235 is transversely carried adjacent the
periphery of a gear 236 mounted on brackets 237 connected to the
box 220. To drive the gear 236, a pinion gear 238 meshed therewith
is carried by shaft 240 journaled in the box 220 and rotated from
the outside of the box by a reversible motor 242 (FIG. 28).
The shutter 230 includes depending legs 241 with slots 242 therein
arranged perpendicular to the axis of pin 235 carried by gear 236.
Similarly, the shutters 232 include slots 243 arranged
perpendicular to the axis of pin 235.
In order to more fully understand the operation of the shutter
operating mechanism reference is made to FIG. 30 wherein it is
shown in a cycle "start" position in that shutter 230 is retracted
and elevator 246 is in its upward position for receipt of the
sample container to be counted. Gear 236 is rotated to a position
wherein pin 235 enters the slot 242 of top opening shutter 230
depending legs 241. The side opening shutters 232 are in a closed
position to the right as viewed in FIG. 30 so that they cover the
photomultiplier tube entry openings.
The elevator carrying the sample container (not shown) at this
point moves downwardly until the sample container is positioned
within the box 220 between the photomultiplier tubes. Gear 236 with
pin 235 continues to rotate clockwise through an angle of
approximately 180.degree. driving shutter 230 to the right to where
it is shown in FIG. 31. At this point the top entry opening is
sealed with the container held in position in the counting station
by elevator 246.
Gear 236 with pin 235 still continues to rotate clockwise with pin
235 entering slots 243 of shutters 232 and after approximately
180.degree. rotation the shutters 232 are moved to the left as
shown in FIG. 32 and the photomultiplier tubes may then be moved
axially toward the container in the counting station.
After counting has been completed the tubes retract and gear 236
with pin 235 rotate in the opposite or counterclockwise direction
first closing shutters 232 and then opening shutter 230 in
successive 180.degree. angles of rotation. When shutter 230 has
been opened, elevator 246 may then move upwardly and the shutters
and elevator are back in the positions shown in FIG. 30 in
readiness for another cycle.
Turning to FIG. 33, there is shown another modified arrangement for
transferring individual sample containers 250 into a counting
station between a pair of axially shiftable photomultiplier tubes
PMT No. 1,PMT No. 2. In the present instance, there is provided a
sliding shuttle bar 252 having a slotted opening 254 therein
adapted to receive a sample container. The shuttle has a first
sealing ring 256 which may be made of felt or the like fixedly
mounted adjacent the end toward the counting station and a second
sealing ring 258 which may be slidable with respect to the shuttle
so that when the shuttle moves a sample container into the counting
station as shown in phantom in FIG. 33, the sealing rings are
disposed on opposite sides thereof to prevent entry of ambient
light.
As an alternative to the sliding, sealing ring, there is shown in
FIG. 34 a pair of resilient rollers 260 which provide a rotatable
seal permitting the shuttle to pass between the nips thereof while
preventing entry of light to the counting station. The rollers
include a shaft-like central portion 262 of a first diameter and
end portions 264 of a larger diameter. The central portion rollers
are of a length corresponding to the height of the shuttle along
the vertical axis as viewed in FIG. 34 while the end portions 264
overlap and engage one another approximately at the middle of the
width of the shuttle along the horizontal axis.
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