Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
1998-07-14
2001-05-08
Moller, Richard A. (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C073S29000R
Reexamination Certificate
active
06227053
ABSTRACT:
MICROFICHE APPENDIX
A Microfiche Appendix is attached hereto and forms a part of this application. The Microfiche Appendix includes 1 microfiche with a total of 88 frames.
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
1. Field of the Invention
This invention relates to the profiling of containers using an ultrasonic liquid level sensor to detect a series of data points that are processed to determine information about the containers, such as container type, whether the container is capped, and, if the container is not capped, the liquid level in the containers.
2. Background of the Invention
A variety of different types and sizes of test tubes and inserts (such as Ezee Nest® tubes that are inserted into ordinary Vacutainer® test tubes or sample cups that are inserted into Microtainer® holders), generically “containers” (or “vessels”), are currently in use in laboratories and hospitals throughout the world. However, there are only a few such containers that comprise the majority of containers in use. These include the Vacutainer® test tubes and Microtainer® holders, both manufactured by the Becton-Dickinson Corporation, test tubes from Sarstedt of Germany, and the two types of inserts mentioned above: Ezee Nest® inserts and Microtainer® holders. Other test tubes are manufactured by Braun of Germany, Meditech, Inc. of Bel Air, Md., and Greiner, among others. The below discussion refers to the Vacutainer® and Sarstedt test tubes and the inserts but would apply equally to other test tubes and other containers as long as sufficient information is provided to the workstation software for the system to identify the containers and distinguish them from other containers.
The Vacutainer® test tubes are available in 4 sizes, 13 mm (diameter)×75 mm (height), 13 mm×100 mm, 16 mm×75 mm, and 16 mm×100 mm. All of these Vacutainer® test tubes may be capped with a rubber stopper or a rubber Hemoguard® cap. The test tubes that are 75 mm in height may alternatively have an Ezee Nest® insert, which holds a small amount of a sample, inserted into the top of the Vacutainer® test tube to be supported by the lip of the test tube. The Sarstedt test tubes are available in two sizes: 16 mm×75 mm and 16 mm×92 mm and may be capped with unique twist-on caps. The other referenced test tubes likewise have unique features, such as size, that are sufficient to identify them.
Some of the various types of containers referred to above are shown in FIG.
1
. The containers are numbered
1
-
19
and identified in the identification key on FIG.
1
. The maximum height of each container is listed below the figure of that container. The listed height includes the height of the container plus any additional height due to the height of the cap or insert.
It is important to be able to process the different types of containers in an automated analytical instrument while requiring as little human intervention, such as data entry of information about the containers, as possible. It would therefore be useful to have an analytical instrument that dynamically determines the container type and liquid level in the container. Similarly, the instrument should also be able to detect capped test tubes in order to know which test tubes must be automatically decapped at an automatic decapping area of the instrument before further processing of the test tubes.
It is further desirable to maximize the throughput of the analytical instrument. One way to maximize throughput is to minimize the downward travel of a probe for aspirating liquid samples from the containers by maximizing the speed with which the probe may be lowered. The probe must enter the liquid slowly so as not to enter the liquid surface at a high velocity, which would perturb the hydraulic interface at the probe tip. If the liquid level in each container is known before the probe is lowered, the probe may be quickly lowered to slightly above the liquid level and a capacitive liquid level sensor on the tip of the probe may be used to lower the probe the additional small distance necessary to enter the sample. This speeds up the cycle time in which each sample is aspirated, as otherwise the probe would have to be lowered at a steady, slow rate until the probe determines the liquid level. To lower the probe more quickly requires a specific acceleration/deceleration motion profile determined by the location of the top surface of the liquid.
An ultrasonic sensor may be used to detect objects not in contact with the sensor. (
FIG. 2
) The ultrasonic sensor comprises a transducer
21
with a piezoelectric tip mounted in a sensor holder
20
. Transducer
21
alternates between operating as a transmitter and receiver. When operating as a transmitter, an electrical pulse is applied to transducer
21
, causing transducer
21
to ring at a particular ultrasonic frequency, which is in the range of approximately 50 kHz to 2 MHz. Transducer
21
rings freely until it eventually stops ringing. The ringing transmits an ultrasonic burst, represented by arrow
23
, for a length of time that is dependent on the pulse width applied to transducer
21
and the size of transducer
21
.The ultrasonic burst has a greater amplitude when initially generated and then attenuates over time. (
FIG. 4
) The burst propagates through air toward a targeted surface, such as surface
22
, and, when it strikes the targeted surface, at least a portion of the wave which is not absorbed by the surface, if any, is reflected back toward sensor
21
as one or more echoes
24
. The sensor is able to detect the echoes after it has finished ringing and is switched to a receive mode.
The ultrasonic burst propagates as a cone-shaped wave. Referring to
FIG. 3
, where a first surface
25
has an aperture
26
, the burst will impinge upon the first surface
25
and pass through the aperture
26
to impinge on a second lower surface
29
, if any. The burst is reflected back from the first, closer surface
25
as a first echo
27
and from the second, farther surface
29
as a second echo
28
, which arrives at sensor
21
after the first echo
27
. The time it takes for each ultrasonic burst to travel from sensor
21
and to return back to sensor
21
as one or more echoes is captured in memory. Software, known to those skilled in the art and typically included by the sensor manufacturer in a printed wire assembly (referred to below as a data acquisition board) which is designed to operate with the sensor, then converts the time measurements to measurements of the distance which the ultrasonic bursts have traveled using the known speed of sound (which equals 331.36 m/sec at ambient temperature).
An ultrasonic sensor may be used in a variety of applications to take measurements over a wide range of distances. They may be used as short range sensors to take measurements as close as a few centimeters away from the sensor or as long range sensors to take measurements as far away as a few meters. Ultrasonic sensors have typically been used in applications such as detecting and identifying solid objects, measuring the shape and orientation of a workpiece, detecting possible collisions between objects to avoid the collisions, room surveillance, flow measurement, and determining a type of material by measuring the absorption of sound.
Ultrasonic liquid level sensing is a known process that uses an analog ultrasonic sensor to measure the level of liquid in a container without physically contacting the liquid. One such sensor that may be used for ultrasonic liquid level sensing is described in U.S. Pat. No. 5,507,178 assigned to Cosense, Inc. of Hauppauge, N.Y. Cosense also manufactures an ultrasonic micro measurement system ML-102, which may be used for liquid level sensing. Ultrasonic sensors are better
Cohen Beri
Landier Olivier
Purpura Paul E.
Waters Ralph
Bayer Corporation
Klawitter Andrew L.
Moller Richard A.
Paolino John M.
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