U.S. patent application number 10/027663 was filed with the patent office on 2002-05-09 for autosampler.
Invention is credited to Goenner, Winfried, Groeschner, Donald L..
Application Number | 20020053244 10/027663 |
Document ID | / |
Family ID | 26821096 |
Filed Date | 2002-05-09 |
United States Patent
Application |
20020053244 |
Kind Code |
A1 |
Goenner, Winfried ; et
al. |
May 9, 2002 |
Autosampler
Abstract
An autosampler for manipulating a specimen container into and
out of a furnace of a parent instrument is disclosed. The
autosampler has upper, lower and middle gripping fingers which grip
and stabilize a crimped wire, which has a large bend therein. The
middle gripping finger is positioned between and opposed to the
upper and lower gripping finger and has a portion at one end
thereof sized and shaped to receive the bend of the crimped wire.
The gripping fingers grip and hold the crimped wire while a tray
table moves to place the specimen container on a hook at the bottom
of the crimped wire. If the specimen container is sealed, a hole
may be punctured therein by a puncturing apparatus, which has a
housing which is movable between an upper and lower position and
biased toward the lower position. A pin is positioned inside the
housing. When the specimen tray moves into the upper position, the
sealed specimen container moves the housing from the lower position
to the upper position thereby exposing the pin and causing it to
puncture the sealed specimen container. An electrostatic discharge
device which includes a housing having a channel thereabout is also
provided. A high voltage source is electrically connected to a pin
positioned inside the housing and in fluid communication with the
channel for supply voltage to the pin and generating multiple free
ions as a result thereof. Pressurized gas directs the free ions
toward an electrostatic field to neutralize the ions therein.
Inventors: |
Goenner, Winfried;
(Uberlingen, DE) ; Groeschner, Donald L.; (New
Milford, CT) |
Correspondence
Address: |
ST. ONGE STEWARD JOHNSTON & REENS, LLC
986 BEDFORD STREET
STAMFORD
CT
06905-5619
US
|
Family ID: |
26821096 |
Appl. No.: |
10/027663 |
Filed: |
December 20, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10027663 |
Dec 20, 2001 |
|
|
|
09518466 |
Mar 3, 2000 |
|
|
|
60122992 |
Mar 5, 1999 |
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Current U.S.
Class: |
73/864 |
Current CPC
Class: |
G01N 35/0099 20130101;
G01N 35/04 20130101 |
Class at
Publication: |
73/864 |
International
Class: |
G01N 001/00 |
Claims
What is claimed is:
1. An apparatus for manipulating a specimen container comprising: a
parent instrument comprising a crimped wire having two ends
defining an axis therebetween, the crimped wire having at least one
point which is displaced from the axis; an autosampler, operatively
connected to the parent instrument, comprising: a gripper assembly
movable between an open and a closed position; at least one
specimen tray positioned about the gripper assembly and having a
plurality of recesses therein for receiving at least one specimen
container, the specimen tray movable between an upper and a lower
position and rotatable about a central axis; and wherein when the
gripper assembly is in the closed position it grips the crimped
wire about the point at which it is displaced from the axis and
stabilizes it while the specimen tray moves so as to attach the
specimen container to the crimped wire.
2. The apparatus of claim 1 wherein the gripper assembly further
comprises: an upper and a lower gripping finger, each finger having
two ends, each finger having one end with a substantially V-shaped
portion for receiving the crimped wire therein; and a middle
gripping finger having two ends, the middle gripping finger
positioned between and opposed to the upper and lower gripping
finger and having a portion at one end thereof sized and shaped to
receive the crimped wire at the point where the crimped wire is
displaced from its axis; and wherein the middle gripping finger
cooperates with the upper and lower gripping fingers to grip and
stabilize the crimped wire.
3. The apparatus of claim 1, wherein at least one of the recesses
of the specimen tray has at least one beveled edge to facilitate
placement of the specimen container.
4. The apparatus of claim 1, wherein at least one of the recesses
of the specimen tray is shaped so that the specimen container is
properly positioned therein.
5. The apparatus of claim 4, wherein at least one of the recesses
of the specimen tray is substantially rounded.
6. The apparatus of claim 1 further comprising an apparatus for
puncturing a hole into the specimen container, the puncturing
apparatus comprising: a housing operatively connected to the parent
instrument, the housing movable between an upper and lower position
and biased toward the lower position; a pointed object housed
inside the housing; and wherein when the specimen tray moves into
the upper position, the specimen tray moves a specimen container
positioned in one of the recesses of the specimen tray and under
the pointed object upward forcing the housing to move from the
lower position to the upper position thereby exposing the pointed
object and causing it to puncture the specimen container.
7. The apparatus of claim 6 wherein the puncturing apparatus
further comprises a spring, housed inside the housing, for biasing
the housing toward the lower position.
8. The apparatus of claim 7 wherein the puncturing apparatus
housing includes a slot therein, the slot sized and shaped to
receive a hook of the specimen container.
9. The apparatus of claim 1 further comprising an electrostatic
discharge device comprising: an electrostatic discharge device
housing attached to the parent instrument, the electrostatic
discharge device housing having a channel thereabout; at least one
substantially sharp object positioned inside the electrostatic
discharge device housing and in fluid communication with the
channel; a voltage source, electrically connected to the at least
one substantially sharp object for supplying voltage thereto and
generating multiple free ions as a result thereof; a source of
pressurized gas for generating a gas stream, the pressurized gas
source operatively connected to the electrostatic discharge device
housing and in fluid communication with the channel, for forcing
gas through the channel and around the at least one substantially
sharp object; and wherein the gas stream directs the free ions
toward an electrostatic field to neutralize ions therein.
10. The apparatus of claim 9 wherein the at least one substantially
sharp object comprises about seven substantially sharp objects
substantially equidistantly spaced about the channel.
11. The apparatus of claim 9 wherein the voltage source supplies
about 5,000 volts of alternating current.
12. The apparatus of claim 9 wherein the gas comprises air.
13. The apparatus of claim 9 wherein the gas comprises
nitrogen.
14. An instrument for conducting analysis of a plurality of sealed
specimen containers, the instrument comprising: an instrument
housing; at least one specimen tray adjacent to the instrument
housing, the at least one specimen tray having a plurality of
recesses therein and movable between an upper and a lower position;
and an apparatus for puncturing at least one hole into a sealed
specimen container, the puncturing apparatus comprising: a
puncturing apparatus housing removably attached to the instrument
housing, the puncturing apparatus housing movable between an upper
and a lower position and biased toward the lower position; and a
sharp object housed inside the puncturing apparatus housing,
wherein when the specimen tray moves toward the upper position a
sealed specimen container positioned in a recess of the specimen
tray and under the sharp object forces the puncturing apparatus
housing to move from the lower position to the upper position
thereby exposing the sharp object and causing it to puncture the
sealed specimen container.
15. The apparatus of claim 14 wherein the puncturing apparatus
further comprises a spring, housed inside the puncturing apparatus
housing, for biasing the housing toward the lower position.
16. The apparatus of claim 15 wherein the puncturing apparatus
housing includes a slot therein, the slot sized and shaped to
receive a hook of the sealed specimen container.
17. A device for discharging an electrostatic field on at least one
component of a parent instrument, the parent instrument having a
housing, the electrostatic field discharging device comprising: an
electrostatic discharge device housing attached to the parent
instrument housing, the electrostatic discharge device housing
having as channel thereabout; at least one sharp object positioned
inside the electrostatic discharge device housing and in fluid
communication with the channel; a voltage source electrically
connected to the at least one sharp object for supplying voltage
thereto and generating multiple free ions as a result thereof; a
source of pressurized gas for generating a gas stream, the
pressurized gas source operatively connected to the electrostatic
discharge device housing and in fluid communication with the
channel, for forcing gas through the channel and around the at
least one sharp object; and wherein the gas stream directs the free
ions toward an electrostatic field to neutralize ions therein.
18. The electrostatic field discharging device of claim 17 wherein
the at least one sharp object comprises about seven sharp objects
substantially equidistantly spaced about the channel.
19. The electrostatic field discharging device of claim 16 wherein
the gas comprises air.
20. The electrostatic field discharging device of claim 16 wherein
the gas comprises nitrogen.
21. The electrostatic field discharging device of claim 17 wherein
the voltage source supplies about 5,000 volts of alternating
current.
Description
CLAIM OF PRIORITY
[0001] This application claims priority from U.S. Provisional
Patent Application No. 60/122,992 filed Mar. 5, 1999.
FIELD OF THE INVENTION
[0002] The present invention relates to an automatic sampling
device and, in particular, to a device that automatically transfers
a sample container from a sample tray to known laboratory analyzing
equipment, for the examination of, for example, the heats of
transformation of a sample, and which transfers the sample
container from the analyzing equipment to the sample tray.
BACKGROUND OF THE INVENTION
[0003] It is known to use thermal gravimetric analysis (TGA)
systems to conduct thermal analyses of selected samples, also
referred to herein as specimens, in order to examine certain
characteristics of the samples as a function of temperature. As it
is sometimes necessary to carry out measurements on a large number
of samples, it is desirable and known in the art to mechanize the
manipulation of the specimens. Such mechanization is commonly
referred to as autosampling.
[0004] One autosampler is shown in U.S. Pat. No. 5,398,556 to Lang.
Lang discloses a device having a vertical gripper member and a
rotatable specimen plate for holding a plurality of specimen
containers. A specimen container is transferred to the measuring
location in the parent machine (e.g., a TGA) by rotating the
specimen plate so that the desired specimen container is positioned
under the gripper. Then, the gripper, which is driven by a motor,
is lowered and gripping fingers attached to a gripping member grip
the specimen container. The container is then raised from the
specimen plate by raising the gripping member. The specimen plated
is then rotated until a recess in the specimen plate is located
underneath the gripping member. Next, the gripping member is
lowered through the recess in the specimen plate and the specimen
container is placed at the measuring location, which is directly
underneath the gripper. The specimen container is then deposited on
the measuring location by releasing the gripper fingers.
[0005] A disadvantage of the gripper taught by the Lang patent is
that the device is relatively complicated in that it has many
moving parts and that if the motor over- or under-drives the
gripper, an error could occur in the placement of the sample.
[0006] In conventional thermogravimetric analysis machines, samples
are placed in a crucible or sample container that is positioned in
a furnace on a platinum ribbon attached to an automatic recording
balance. Conventional TGAs are disadvantageous because the platinum
wire is easily bent with even a very small force by the gripper
when it moves the crucible on and off the balance. After the
platinum wire is bent, it is virtually impossible to move back into
its original position. If the device is used with a bent wire, it
is extremely difficult to accurately position the crucible within
the furnace. Further, the act of replacing the platinum wire
typically decreases the sensitivity of the machine and
detrimentally effects its performance.
[0007] Known autosamplers are also disadvantageous because static
electricity may accumulate in the furnace area. This is frequently
a serious problem which detrimentally effects analytical results.
The static buildup generally occurs on the surface of the glassware
surrounding the TGA furnace and is aggravated by movement of the
glassware over insulating material, such as an O-ring. The
resulting electrostatic fields attract the sample container to the
surface of the glassware, thus moving the sample container off
balance and jeopardizing the advancement of the analysis.
Additionally, static electricity may pull some of the sample from
the sample pan if the sample pan contains some dust-like
particles.
[0008] Devices and methods are known to reduce or eliminate static
electricity. For example, there are solutions which may be wiped
onto glass surface areas. Unfortunately, these known solutions may
leave behind a residue which can undesirably build-up on the glass
and adversely effect the test results. Alternately, an operator may
point a hand-held ion generating device at the area. However, such
is undesirable because it requires the operator to stay in the
vicinity of the autosampler during the course of the sampling,
which can be many hours, and, because the static electricity is not
visible, the operator may miss the problem area. Additionally,
radioactive emitters are available. However, these are
disadvantageous because they have strict disposal requirements.
[0009] As is known, conventional autosamplers comprise a sample
tray table having a plurality of recesses for holding each of the
sample containers in place while the analysis is being conducted.
Conventional sample tray tables, however, are disadvantageous
because they do not facilitate placement of the sample pan into the
recess.
[0010] Sometimes it is necessary to work with sealed sample
containers, such as when the contents of the sample container are
volatile. If a sample container is sealed, it is necessary to
puncture the top of the sealed container prior to placing it into
the furnace. Conventional puncturing devices are disadvantageous,
however, because they have several moving parts and are relatively
complicated. Further, disadvantageously, it is sometimes necessary
to puncture a sample manually before it is loaded into the tray.
When this is done, the sample sometimes loses some of its
properties before being loaded into the furnace.
[0011] What is desired, therefore, is an autosampler which has a
gripper assembly that cooperates with a hanging wire, wherein the
hanging wire is not easily bent or damaged and wherein the hanging
wire may be easily replaced without reducing the sensitivity of the
parent instrument, which is operably connected to an electrostatic
discharge device, which has a sample tray table with recesses that
facilitate placement of the sample container into the recesses, and
which is operatively connected to a safe and reliable puncturing
device.
SUMMARY OF THE INVENTION
[0012] Accordingly, it is an object of the present invention to
provide an autosampler which has a gripper assembly that cooperates
with a hanging wire which is durable and not easily damaged.
[0013] It is another object of the present invention to provide an
autosampler which cooperates with a hanging wire assembly that can
be easily replaced without reducing the sensitivity of the parent
instrument.
[0014] It is still another object of the present invention to
provide an autosampler which has a sample tray table with beveled
edges and rounded recess areas to facilitate placement of the
sample pan into the recesses of the sample tray table.
[0015] It is yet a further object of the present invention to
provide an autosampler which is operatively connected to an
electrostatic discharge device that is safe, effective and easy to
use.
[0016] It is still another object of the present invention to
provide an autosampler which is operatively connected to a
puncturing device which has no motorized parts and which is
relatively inexpensive to manufacture and simple to construct.
[0017] It is still a further object of the present invention to
provide an autosampler which is reliable, easy to use, and
cost-effective to manufacture and maintain.
[0018] To overcome the deficiencies of the prior art and to achieve
the objects and advantages listed above, an autosampler is
disclosed which comprises'a novel gripping assembly which is
uniquely sized and shaped to stabilize a crimped wire which hangs
from an arm of a balance of the parent instrument. After the
gripping assembly grips and stabilizes the wire, a tray table.
which is positioned about the gripping assembly, moves vertically
and rotationally to position a specimen container onto a hook at
the bottom of the crimped wire and substantially reverses its steps
to remove the container from the crimped wire.
[0019] The crimped wire is uniquely designed to be received by the
gripping apparatus. The crimped wire has two ends defining an axis
therebetween and has at least one point which is displaced from the
axis, i.e., the hanging wire is substantially bent at at least one
location.
[0020] More particularly, the gripper assembly comprises upper,
middle and lower gripping fingers, which are movable between an
open and a closed position. The upper and lower fingers each have a
V-shaped portion at one end for receiving the crimped wire therein
and aligning the crimped wire above and below its bend. The middle
gripping finger has two ends and is positioned between, and opposed
to, the upper and lower gripping finger. The middle gripping finger
has a portion at one end thereof sized and shaped to receive the
crimped wire at the bend. When the gripping fingers are in the
closed position, they grip the crimped wire and stabilize it while
the specimen tray moves so as to connect the specimen container to
the hook of the crimped wire.
[0021] Additionally, the autosampler is operatively connected to an
apparatus for puncturing holes into the top of a sealed specimen
container. The puncturing apparatus comprises a housing, which is
operatively connected to the parent instrument and which is movable
between an upper and a lower position. A spring biases the housing
into the lower position. A sharp object, such as a pin, is housed
inside the housing. When a sealed specimen container is positioned
under the sharp object, movement of the tray table to its uppermost
position causes the container to force the housing to move from the
lower position to the upper position thereby exposing the sharp
object. This causes the sharp object to puncture the sealed
specimen container.
[0022] Additionally, the autosampler is operatively connected to an
electrostatic discharge device which reduces or eliminates
electrostatic fields which are formed on the surface of glassware
of the furnace and on the surface of the autosampler tray and
gripper assembly. The electrostatic discharge device comprises a
housing which is removably attached to the parent instrument; the
housing has a channel thereabout. At least one pin, but preferably
a plurality of pins, is positioned inside the housing and in fluid
communication with the channel. A source of high voltage
alternating current is electrically connected to each pin and
supplies voltage to the pins. This generates multiple free ions
which cancel the electrostatic field. A source of pressurized gas,
such as nitrogen or air, is operatively connected to the housing
and forces gas through the channel and around the pins and directs
the free ions toward an electrostatic field to neutralize the ions
therein.
[0023] The invention and its particular features and advantages
will become more apparent from the following detailed description
when considered with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is an isometric view of an autosampler, constructed
in accordance with the present invention;
[0025] FIG. 2 is a side isometric view of the autosampler shown in
FIG. 1, showing a crucible hanging from a hanging wire assembly and
a gripping assembly in the open position;
[0026] FIG. 3 is a side isometric view of the autosampler similar
to the one shown in FIG. 2, wherein the autosampler has moved to a
"mid" position;
[0027] FIG. 4 is a side perspective view of the balance of the
parent instrument, showing the hanging wire assembly on one end
thereof;
[0028] FIG. 5 is a side plan view of the hanging wire assembly;
[0029] FIG. 6 is an isometric view of the gripper assembly in the
closed position;
[0030] FIG. 6A is a top view of the gripper assembly of FIG. 6;
[0031] FIG. 6B is a top view of the gripper assembly of FIG. 6
shown in the open position;
[0032] FIG. 7 is a bottom perspective view of an electrostatic
discharge device constructed in accordance with the present
invention;
[0033] FIG. 8 is an exploded view of the top of the electrostatic
discharge device shown in FIG. 7;
[0034] FIG. 9 is an exploded view of the bottom of the
electrostatic discharge device shown in FIG. 7;
[0035] FIG. 10 is a schematic diagram of electrostatic discharge
device shown in FIG. 7;
[0036] FIG. 11 is a top schematic view of a sample tray table shown
in FIG. 1;
[0037] FIG. 12 is an enlarged and broken away view of a recess in
the sample tray table shown in FIG. 11;
[0038] FIG. 13 is a cross-sectional view of a puncture device which
is operatively connected to the autosampler shown in FIG. 1,
constructed in accordance with the present invention; and
[0039] FIG. 14 is a top view of the autosampler shown in FIG. 1
with the cover removed for clarity.
DETAILED DESCRIPTION OF THE INVENTION
[0040] Referring to the drawings in detail, an autosampler is shown
and generally designated by the reference numeral 10. It should be
noted that for the sake of clarity not all of the components and
parts of auto sampler 10 may be shown and/or marked in all the
drawings. As used in this description, the terms "up", "down",
"top", "bottom", etc., refer to autosampler 10 when in the
orientation illustrated in FIG. 1.
[0041] Referring now more particularly to FIG. 1, autosampler 10 is
designed to be used with, and operatively connected to, a parent
instrument 12, for example, a thermal gravimetric analysis (TGA)
machine. As is known, TGA machines conduct thermal analyses of
selected samples in order to examine certain characteristics of the
samples as a function of temperature. It should be understood that
autosampler 10 may be used with other analytical instruments known
in the art, after obvious modifications that will become apparent
after reading this description. Discussion herein has been limited
to the TGA for convenience only and is not intended to be
limiting.
[0042] Before operations begin, operational data can be provided to
a computer (not shown) of the autosampler 10 by an operator through
a keyboard (not shown) with a display means (not shown), all of
which are known in the art. Alternatively, the computer of the
autosampler 10 may be driven by a computer program provided by a
host computer (not shown), such as the one marketed by Perkin-Elmer
Corporation known in the field by the trademark Pyris 1.TM..
[0043] As is known, parent instrument 12 generally comprises a
furnace 14 (FIG. 3) for heating specimen container. Furnace 14 is
operatively connected to Pyris 1 software, and capable of heating
up to temperatures of about 1000.degree. C. or more. Furnace 14
comprises a conventional heating element 15 (FIG. 3) and is movable
along a vertical axis between an upper and lower position. When in
the uppermost position, glass top 16 seals against O-ring 18.
[0044] As best shown in FIGS. 4 and 5, parent instrument 12 also
comprises a conventional and extremely sensitive balance or weight
measuring apparatus 20. Balance 20 has two arms 22, 24. A
conventional tare weight 26 hangs from one arm 24. Arm 22 contains
a series of wires or ribbons which serve to hold a specimen
container 28 (FIG. 2).
[0045] More specifically, a glass sphere 30 is removably positioned
on top of a hollow glass tube 32 and held in place by flange 34 and
an adhesive 36,such as rubber cement, which is known in the art. A
ribbon 38, preferably made of platinum, extends through the chamber
of hollow glass tube 32 and is connected to sphere 30. Ribbon 38 is
rotatable in the direction shown by arrow 40. Ribbon 38 has a loop
42 formed at one end thereof.
[0046] In conventional parent instruments, wire members which hold
the specimen container during the analysis have been known to
break. When the wire breaks or bends, it must be replaced.
Disadvantageously, the sensitivity of the balance of prior art
devices is typically damaged or destroyed during the replacement
process. Advantageously, and unlike prior art instruments, the use
of the removable adhesive 36 and flange 34 to position platinum
ribbon 38 renders ribbon 38 easily replaceable. Further, when
ribbon 38 is replaced, the sensitivity of balance 20 is not damaged
or destroyed.
[0047] Crimped wire 46 having hook 44 is positioned in loop 42 of
ribbon 38. Crimped wire 46 can be made of any suitable material but
is preferably made of nichrome or quartz. Crimped wire 46 has two
ends defining an axis 48 therebetween. Advantageously, crimped wire
46 has at least one point 50 which is displaced from axis 48, i.e.
includes a bend. In the preferred embodiment, the angle formed by
members 52, 54 at location 50 is about 90.degree.. Crimped wire 46
has hook 56 formed at the end thereof for connecting specimen
container 28 (FIG. 2) thereto.
[0048] Referring in detail to FIGS. 1-3. autosampler 10 is
removably fixed and operatively connected to parent instrument 12.
Autosampler 10 comprises at least one specimen tray 58, also shown
in FIGS. 11 and 12. Tray 58 has a plurality of recesses 60 for
receiving specimen container 28 (FIG. 2). Preferably there are at
least 20 recesses, but it should be understood that as many
recesses could be formed as necessary.
[0049] Each of the recesses is given a unique identifying number
for easy sample identification. At least one, and preferably all,
of the recesses 60 has at least one beveled edge 62 to facilitate
placement of the specimen container 28 therein (FIG. 12). Also, it
is preferable that each recess 60 be uniquely shaped so that the
specimen container 28 is always properly positioned and oriented
therein. Still further, it is preferred that at least one of the
recesses of the specimen tray be substantially rounded to
facilitate placement of the specimen container 28 therein.
[0050] Specimen tray 58 is movable via a conventional stepper motor
59 and a slip clutch and electromagnetic brake assembly 61 between
an upper and lower position as indicated by arrow 64 and rotatable
in the direction shown by arrow 66 about a central axis 68 (see
FIGS. 2 and 14). Any suitable stepper motor known in the art may be
used. In the embodiment, a stepper motor having the following
operational characteristics is preferred: 12 volts DC; 0.3 amps; 2
phase; and 0.9 mm/step.
[0051] A second stepper motor 63 (FIG. 14) swings autosampler 10
toward (FIGS. 1 and 2) and away from (FIG. 3) the specimen load
position. This stepper motor may have the following operational
characteristics: 12 volts DC; 0.3 amps; 2 phase; and 0.9 mm/step.
Autosampler 10 is attached to the parent instrument 12 via a pivot
shaft 65 (FIG. 1). Autosampler 10 is movable between a loading and
an unloading position and, when not loading or unloading,
autosampler 10 moves to a "safe" location, i.e., away from the load
position, where the specimen is analyzed.
[0052] Movement by these two motors, together with a gripper motor
67 (discussed below), allows gripping assembly 70 (discussed in
detail below) to access each container 28, transfer it from the
specimen tray 58 and attach it to hook 56 of crimped wire 54, and
return it to its appropriate position on the sample tray 58 after
the analysis is completed. It should be understood, however, that
any suitable means known in the art may be used to move autosampler
10, such as mechanical, hydraulic or magnetic means, or
combinations thereof.
[0053] Referring to FIGS. 2, 3, 6, 6A and 6B, autosampler 10
further comprises a gripper assembly 70 operatively connected to
specimen tray 58 and movable between an open position (shown in
FIGS. 2, 3 and 6B) and a closed position (FIGS. 6 and 6A). When
gripper assembly 70 is in the closed position, it grips crimped
wire 46 about the point 50 (FIG. 5) at which it is displaced from
its linear axis, and stabilizes it while the specimen tray 58 moves
so as to connect the specimen container 28 to the crimped wire
46.
[0054] More specifically, gripper assembly 70 comprises upper,
middle and lower gripping fingers 72, 74, 76, respectively (each
finger may not be shown in all the drawings). Each finger 72, 74,
76 may be made of any suitable material, however, they are
preferably made of aluminum.
[0055] In one embodiment, the upper 72 and lower 76 gripping finger
are substantially identical in design. Each gripping finger has two
ends with a substantially V-shaped portion 80 cut therefrom for
receiving crimped wire 46 therein.
[0056] Middle gripping finger 74 is positioned between the upper
and lower fingers 72, 76, respectively, and, as best shown in FIGS.
2, 6 and 6B, opposes fingers 72, 76. Middle finger 74 has two ends
and a portion 78 at one end thereof sized and shaped to receive
crimped wire 46 at the point 50 where crimped wire 46 is maximally
displaced from its axis 48. As shown in FIG. 6A, when in the closed
position, middle gripping finger 74 cooperates with the upper and
lower gripping finger 72, 76, to grip and stabilize crimped wire 46
so that specimen container 28 may be positioned on hook 56.
[0057] Middle gripping finger 74 is designed to push against
crimped wire 46 at the location of the angle formed by members 52,
54. It should be understood that any suitable size angle could be
formed by members 54, 56 and any suitable cutout portion of finger
74 could be used so long as middle finger 74 cooperates with
fingers 72, 76 to stabilize crimped wire 46 while specimen
container 28 is loaded and unloaded.
[0058] Gripping fingers 72, 74, 76 are biased to a closed position.
Fingers 72, 74, 76 may use any suitable means to move between an
open and closed position, such as hydraulic, mechanical and
magnetic means and/or combinations thereof. In one embodiment, a
motor 67 (FIG. 14) turns a cam (not shown) which simultaneously
activates the fingers. Although any suitable conventional motor may
be used, in one embodiment, a motor having the following
operational characteristics is used: 12 volts DC; 0.3 amps; 2
phase; and 0.9 mm/step.
[0059] As discussed above, static build up generally occurs on the
surface of the glassware surrounding the TGA furnace 14, and is
aggravated by movement of the glassware 16 over insulating
material, such as O-ring 18. The resulting electrostatic fields
negatively influence the readings of the highly sensitive
microbalance 20 of the parent instrument 12 because the sample
container 28 is moved off-center due to its attraction to the
surface of the glassware. Advantageously, parent instrument 12
comprises an electrostatic discharge device 82, which is best shown
in FIGS. 3, 7, 8 and 9, which substantially reduces and/or
eliminates the electrostatic fields described above.
[0060] Electrostatic discharge device 82 comprises a housing 84
which is operatively and removably attached to parent instrument
12, and is most preferably mounted above the TGA furnace 14. The
housing 84 surrounds the uppermost portion of the furnace assembly
14 and is therefore in close proximity to the region of static
buildup.
[0061] Discharge device 82 comprises at least one, and preferably a
plurality of, substantially sharp objects 86, such as heavy-duty
metal pins (see FIG. 9). Each of the pins 86 are substantially
equidistantly positioned about a metallic ring 88 through a
circular cavity 87 (FIG. 7). Each cavity 87 is sufficiently deep so
that the pins 86 are not directly exposed to the touch and the
walls of each cavity 87 are angled to direct the ions toward the
electrostatic field. As the pinpoints wear due to normal use over
extended periods of time, the production of ions at each point may
diminish. Advantageously, each pin 86 may be easily replaced to
restore full production of ions.
[0062] A voltage source is electrically connected to each pin 86
for supplying voltage to the pin 86 and generating multiple free
ions as a result thereof. Any suitable voltage amount may be used:
in the most preferred embodiment about 5,000-6,000 VAC is used (see
FIG. 10).
[0063] Referring again to FIGS. 8 and 9, above the metallic ring 88
is a gas plenum 90 that feeds a low-pressure gas stream from a gas
source 94 into each cavity 87 which is in fluid communication
therewith. Preferably, compressed air or nitrogen is used. The gas
stream causes the positive and negative free ions generated at the
pinpoints 86 to be propelled downward toward the furnace 14. The
combined flow from each cavity 87 (FIG. 7) effectively blankets the
furnace area 14 with free ions that neutralize electrostatic fields
on the glassware above and below O-ring 18, i.e., the top half of
the furnace, and on the surface of the autosampler tray 58 and
gripper assembly 70.
[0064] A schematic diagram of the electrostatic discharge device 82
is shown in FIG. 10. The low-pressure gas source 94 is connected
from within the analytical instrument 12 to the gas plenum within
the housing 84 through a port in the housing 84. Any suitable,
standard flexible tubing and fittings may be employed to connect
the gas source 94 to the housing 84. A second port connects the
high voltage, alternating current source 98 to the metallic ring 88
within housing 84 via resistive element 99. The second port is
comprised of a long insulating tube 96 that extends into the
discharge device 82. Conventional resistive element 99, nominally
about eight megohms, is housed inside tube 96 and limits electrical
current flow into the pinpoint 86 should a short circuit occur or
in the event that the operator of the TGA 12 comes into contact
with any of the metallic elements of device 82. Conventional high
voltage AC transformer 98, housed inside the parent instrument 12,
is advantageously designed to limit self-generation of ions within
its own environment.
[0065] Activation of both the low-pressure gas source 94 and the
high voltage transformer 98 are controlled by a microprocessor 100,
electrically and operatively connected to interface electronics 102
housed inside the parent instrument 12. Discharge device 82 may be
activated manually or automatically by entering the appropriate
command into the Pyris 1 software from the keyboard of the host
computer. Preferably, the gas and high voltage supplies 94, 98,
respectively, are turned on immediately prior to the separation of
the upper and lower halves of the furnace 14. While the furnace 14
is separated, the ionization device 82 remains on so that
components of the furnace 14 and the sample handling area are
flooded with ions.
[0066] Advantageously, the discharge device 82 is designed so that
it automatically stops operating if the furnace 14 remains open (as
shown in FIG. 3) for a long period of time, such as greater than
three minutes. This reduces the amount of ozone produced by the
discharge device 82 and reduces the operator's exposure to the high
voltage within the housing assembly 84.
[0067] When the furnace assembly 14 is commanded to close, the
ionization device remains on, or turns on again as the case may be.
The time to close the furnace 14 is programmable, thereby allowing
adequate time to discharge lingering electrostatic fields. All
timing related changes are made by modifying the control firmware
(not shown) within the microprocessor 100.
[0068] Parent instrument 12 also comprises an apparatus 104 for
puncturing holes into the top of a sealed specimen container 28,
which is best shown in FIG. 13. Puncturing apparatus 104 comprises
a housing 106, operatively connected to parent instrument 12, and
uses the autosampler's sample tray 58 up/down movement to move to
and from a puncture position (FIG. 13) and a rest position (not
shown); that is, puncturing apparatus 104 is movable via the sample
tray 58 between an upper and lower position. Steel spring 108
biases housing 106 into the lower position. It should be understood
that any suitable means may be used to bias housing 106 into the
lower position.
[0069] A sharp or pointed object 110, such as a pin, is housed
inside the puncturing device housing 106 for puncturing a hole into
the top of a sealed specimen container 28. Any suitable strong,
sharp object may be used. In the preferred embodiment, a steel pin
is used.
[0070] A slot 112 is formed at the bottom of the housing 106 and is
sized and shaped to receive a hook or handle 114 (FIGS. 2, 3 and
13) of specimen container 28.
[0071] In operation, when the specimen tray 58 (FIGS. 1-3 and 11)
moves into the upper position, the sealed specimen container 28
forces the housing 106 to move from the lower position to the upper
position thereby exposing pin 110 and causing it to puncture the
top of the sealed specimen container 28.
[0072] A method for handling and transferring specimen containers
28 generally follows the operation of autosampler 10 discussed
above and comprises the following steps. First, an operator
programs autosampler 10 and loads specimen containers 28 containing
specimens onto specimen tray 58.
[0073] Gripper 70 begins each session in the open position and tray
58 is in the lowermost position and in a "safe" position, which is
farthest from furnace 14. Autosampler 10 is then instructed by the
operator via software to begin a session, i.e., to pick-up a
particular sample container 28 and to load it into furnace 14.
[0074] Autosampler 10 swings via stepper motor 63 from the "safe"
position to a "mid" position, which is between the "safe" position
and the "loading" position. At the "mid" position, tray 58 rotates
via stepper motor 59 to the desire sample position, which positions
the predetermined container 28 immediately to the left of hook 56
of crimped wire 46.
[0075] Autosampler 10 then swings until it is in a "loading"
position, a position in which it is directly over the lowered
furnace 14. Gripping fingers 72, 74, 76 then close via stepper
motor 67 around crimped wire 46 and stabilize and align it. Tray
table 58 then raises up, rotates counterclockwise to deposit the
hook or handle 114 of container 28 onto hook 56 (see FIGS. 2 and
3). After the container 28 is properly positioned on crimped wire
46, the tray table 58 lowers to its lowermost position via stepper
motor 59 and gripping fingers 72, 74, 76 move via stepper motor 67
to their normally open position. Then, autosampler 10 swings to its
"mid" position where the host computer conducts a quick safety
check and then autosampler 10 swings to the "safe" position via
stepper motor 63.
[0076] Next, furnace 14 moves from its lowermost position to the
upper position and encloses specimen container 14 therein by
forming a tight seal at O-ring 18. Then, the furnace is activated,
the temperature inside the furnace rises to the pre-selected
temperature, and the desired thermogravametric analysis takes
place. The weight differential is measured by balance 20 and
pertinent data is recorded by the host computer.
[0077] After the appropriate test has been completed, the furnace
14 cools down and moves to its lowermost position. Autosampler 10
then prepares to unload the specimen container 20 from the furnace
14. First, autosampler 10 swings from its "safe" position to the
"mid" position. Tray table 58 rotates via stepper motor 59 until
the recess for receiving container 28 is just to the right of
specimen container 28 as it hangs on wire 46, and autosampler 10
rotates to the "load" position. Gripper fingers 72, 74, 76 then
close via stepper motor 67 around wire 46 and stabilize it. Tray 58
then moves via stepper motor 59 to its uppermost position. Table 58
then rotates via stepper motor 59 clockwise and picks up sample
container 28. Table 58 then moves to its lowermost position and
gripping fingers 72, 74, 76 open via motor 67 and remain in the
normally open position. Autosampler 10 then swings to its "mid"
position where a quick safety check is conducted and then swings
again to its "safe" position via motor 63.
[0078] If specimen container 28 is sealed, its top must be
punctured prior to its being placed in furnace 14. Puncturing
device 104 (FIGS. 1 and 13) punctures a hole in the top of sealed
container 28 when instructed by an operator via instructions
entered into the host computer. Puncturing device 104 operates in
the manner discussed above.
[0079] After autosampler 10 has been properly programmed and
loaded, it advantageously operates without further human operator
assistance. Further, the autosampler 10 has the ability with the
Pyris 1.TM. program, when properly programmed, to abort an analysis
if problems occur with the transfer of a specimen container 28 and
to generate an error message which is displayed on the display
screen of the host computer (not shown).
[0080] In its most preferred embodiment, autosampler 10 is capable
of loading up to 20 samples without operator assistance, thus,
freeing the operator to perform other tasks. Advantageously,
because of the safety features built into the autosampler 10, the
operator does not need to be in the vicinity of the autosampler 10
while it is working. Thus, the operator may load autosampler 10
near the end of the work day, and upon returning to work the next
day, find the results of the analysis. As a result, autosampler 10
saves the operator much time and energy.
[0081] It should be understood that the foregoing is illustrative
and not limiting and that obvious modifications may be made by
those skilled in the art without departing from the spirit of the
invention. Accordingly, reference should be made primarily to the
accompanying claims, rather than the foregoing specification, to
determine the scope of the invention.
* * * * *