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United States Patent |
5,751,608
|
Koch
,   et al.
|
May 12, 1998
|
Coating thickness gauge
Abstract
A modular coating thickness gauge includes a probe which generates a signal
representative of coating thickness, a PCMCIA card connected to the probe
for converting the signal into a standard PCMCIA output format, and a
portable computing unit for receiving the signal via the PCMCIA card. The
gauge allows the on-site user to alternately record coating thickness
measurement data and descriptive textual or graphical data relating to
each coating thickness measurement.
Inventors:
|
Koch; Frank J. (Ogdensburg, NY);
Vandervalk; Leon C. (Brockville, CA);
Beamish; David J. (Brockville, CA)
|
Assignee:
|
DeFelsko Corporation (Ogdensburg, NY)
|
Appl. No.:
|
529137 |
Filed:
|
September 15, 1995 |
Intern'l Class: |
G06F 015/52; G01N 023/203 |
Field of Search: |
364/563,560,550,920,921.8
324/230,229
|
References Cited
U.S. Patent Documents
4046994 | Sep., 1977 | Prohaska | 235/61.
|
4059904 | Nov., 1977 | Sato | 33/126.
|
4079237 | Mar., 1978 | Schlesinger | 364/563.
|
4155009 | May., 1979 | Lieber et al. | 250/308.
|
4266875 | May., 1981 | Bodlaj | 356/381.
|
4389706 | Jun., 1983 | Gomola et al. | 364/130.
|
4715007 | Dec., 1987 | Fujita | 364/563.
|
4742879 | May., 1988 | Leifeld | 177/50.
|
4791706 | Dec., 1988 | Wiening et al. | 19/105.
|
4863037 | Sep., 1989 | Stevens et al. | 209/3.
|
4919967 | Apr., 1990 | Handke et al. | 427/8.
|
4934309 | Jun., 1990 | Ledermann et al. | 118/50.
|
4962569 | Oct., 1990 | Hosel | 19/106.
|
4967381 | Oct., 1990 | Lane et al. | 364/551.
|
4974166 | Nov., 1990 | Maey et al. | 364/478.
|
4982477 | Jan., 1991 | Hosel | 19/0.
|
5054620 | Oct., 1991 | DeWitt et al. | 209/3.
|
5054700 | Oct., 1991 | DeWitt | 241/101.
|
5066241 | Nov., 1991 | Hills | 439/260.
|
5097421 | Mar., 1992 | Maney et al. | 364/478.
|
5115918 | May., 1992 | DeWitt et al. | 209/3.
|
5137661 | Aug., 1992 | Kanome et al. | 264/1.
|
5165415 | Nov., 1992 | Wallace et al. | 128/661.
|
5233727 | Aug., 1993 | Baechler | 19/300.
|
5241280 | Aug., 1993 | Aidun et al. | 324/671.
|
5254830 | Oct., 1993 | Zarowin et al. | 219/121.
|
5293132 | Mar., 1994 | Koch | 324/671.
|
5335066 | Aug., 1994 | Yamada et al. | 356/364.
|
5343146 | Aug., 1994 | Koch et al. | 324/230.
|
5467014 | Nov., 1995 | Nix | 324/230.
|
Foreign Patent Documents |
5-185367 | Jul., 1993 | JP.
| |
2 265 985 A | Oct., 1993 | GB.
| |
WO 87/04783 | Aug., 1987 | WO.
| |
WO 89/03020 | Apr., 1989 | WO.
| |
WO 90/02920 | Mar., 1990 | WO.
| |
Other References
Personal Computer Memory Card International Association PCMCIA PC Card
Standard, pp. i through xii, 1-3 through 1-4, 2-1 through 2-4, 3-1 through
3-28, 4-1 through 4-4, Release 2.1, Jul. 1993.
|
Primary Examiner: Voeltz; Emanuel T.
Assistant Examiner: Vo; Hien
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis LLP
Claims
What is claimed is:
1. A method of recording coating thickness measurements, comprising the
steps of:
obtaining a plurality of coating thickness values with a probe electrically
connected to an electronic memory;
recording in the electronic memory the plurality of coating thickness
values; and
recording in the electronic memory a plurality of descriptive data, each
descriptive data is associated with a respective one of the coating
thickness values and provides information concerning the respective one
coating thickness value.
2. The method of claim 1, wherein the steps of recording the coating
thickness values and of recording the descriptive data are performed
alternately.
3. The method of claim 1, wherein the coating thickness values are
transmitted to the electronic memory via a PCMCIA card.
4. The method of claim 1, wherein the descriptive data comprise text.
5. The method of claim 1, wherein the descriptive data are recorded by
transforming text handwritten on a computer screen with a writing
instrument into digital data.
6. The method of claim 1, wherein the descriptive data are defined with
reference to an electronic pictorial representation of a coated article.
7. The method of claim 6, wherein the descriptive data represent locations
on the electronic pictorial representation of the coated article.
8. The method of claim 1, further comprising the step of displaying a
plurality of indicia on a graph on a video display screen, the indicia
representing the plurality of coating thickness values.
9. The method of claim 8, further comprising the step of retrieving one of
the descriptive data by selecting on the graph one of the indicia.
10. An apparatus for measuring a coating thickness, comprising:
a probe which generates a first signal representative of a measured coating
thickness; and
a PCMCIA card connected to the probe and which receives the first signal
from the probe, the PCMCIA card including means for converting the first
signal into a second signal which is compatible with a standard PCMCIA
output format.
11. The apparatus of claim 10, wherein the probe comprises an LC
oscillator.
12. The apparatus of claim 11, wherein the PCMCIA card includes a counter
which measures a frequency of the LC oscillator.
13. The apparatus of claim 10, wherein the probe comprises a permanent
magnet and a Hall sensor.
14. The apparatus of claim 13, wherein the probe further comprises an eddy
current search coil.
15. The apparatus of claim 10, wherein the probe includes means for
discriminating between a ferrous and a nonferrous substrate upon which the
coating is coated.
16. The apparatus of claim 10, further comprising a portable computing unit
which includes a PCMCIA port for receiving the PCMCIA card.
17. The apparatus of claim 16, wherein the portable computing unit includes
a touch-sensitive screen, and the portable computing unit receives
descriptive data from a user via the screen.
18. The apparatus of claim 17, further comprising a pointed writing
instrument for entering the descriptive data.
19. The apparatus of claim 17, wherein the portable computing unit
comprises a memory and is adapted to alternately record in the memory the
descriptive data from the user and numerical data from the second signal
which numerical data represent a coating thickness.
20. The apparatus of claim 19, wherein the descriptive data are defined
with reference to a pictorial representation on the screen of an article
upon which a coating is coated.
21. An apparatus for measuring and recording coating thickness
measurements, comprising:
an electronic memory;
means for obtaining a plurality of coating thickness values with a probe
electrically connected to the electronic memory;
means for recording in the electronic memory the plurality of coating
thickness values; and
means for recording in the electronic memory a plurality of descriptive
data so that each descriptive data is associated with a respective one of
the coating thickness values and provides information concerning the
respective one coating thickness value.
22. The apparatus of claim 21, wherein the coating thickness values are
transmitted to the electronic memory via a PCMCIA card.
23. The method of claim 1, wherein the descriptive data includes textual
descriptions of the associated coating thickness values.
24. The method of claim 1, wherein the descriptive data includes an image
of an object measured to obtain the plurality of coating thickness values.
25. The method of claim 1, wherein the descriptive data provides a
description of a source of the coating thickness values.
26. The apparatus of claim 21, wherein the descriptive data includes
textual descriptions of the associated coating thickness values.
27. The apparatus of claim 21, wherein the descriptive data includes an
image of an object measured to obtain the plurality of coating thickness
values.
28. The apparatus of claim 21, wherein the descriptive data provides a
description of a source of the coating thickness values.
29. The method of claim 1, further comprising the step of inputting the
plurality of descriptive data via an input device prior to recording the
plurality of descriptive data.
30. The apparatus of claim 21, further comprising means for inputting the
plurality of descriptive data.
Description
BACKGROUND
1. Field of the Invention
The present invention relates to coating thickness gauges and more
particularly to a novel method and apparatus for measuring and recording
coating thickness data and associated descriptive data through a graphical
user interface.
2. Description of the Related Art
The art of measuring the thickness of a coating on a substrate has produced
a wide variety of coating thickness gauges for measuring a variety of
materials. In general, coating thickness gauges include a probe which
produces an electronic signal responsive to a measured physical quantity
representative of a coating thickness. For example, when measuring the
thickness of an electrically nonconductive coating on a conductive
substrate, the probe can include an inductor which registers a change in
impedance based on its proximity to the conductive substrate. The
impedance change of the inductor is reflected by a change in frequency in
an LC oscillator which can be mathematically related to the thickness of
the coating.
Conventional coating thickness gauges have also provided the capability of
transforming the electronic signal representative of coating thickness
into digital data and of storing a number of data points for later
downloading and analysis. Typically, the coating thickness measurements
are later sequentially correlated to a written description of the article
being measured. Such a procedure, however, requires the user to manually
keep track of which data points correspond to which locations on the
object being measured, and are thus time consuming and susceptible to
recording errors.
Thus, although coating thickness gauges have been developed to provide very
accurate digital readings, the industry has not yet produced a coating
thickness gauge with a user interface which facilitates recording and
analysis of data, despite the ongoing advances in computer technology.
Prior to the present invention, there was a need in the art, therefore,
for a method and apparatus for measuring and recording coating thickness
data which is easy to use and which ensures accuracy and reliability in
the recording of measurements.
OBJECTS AND SUMMARY
It is an object of the invention to provide a novel coating thickness gauge
which allows a user to record thickness measurement data along with
descriptive data through a user interface on a computer screen.
It is a further object of the invention to improve the accuracy of coating
thickness measurement data by providing an apparatus which allows a user
to alternate between recording a coating thickness measurement data point
and recording descriptive textual or graphical data relating to the data
point.
It is a further object of the invention to provide a modularized coating
thickness apparatus which includes a probe which produces an electric
signal representative of a measured coating thickness and a PCMCIA card
which receives the electric signal and converts the electric signal into a
digital data signal in a standard PCMCIA output format. The coating
thickness apparatus preferably includes a portable computing unit or
Personal Digital Assistant (PDA) with a port for receiving the PCMCIA card
and a screen for providing a graphical user interface.
An exemplary method according to the present invention includes the steps
of obtaining a plurality of coating thickness values with a probe
electrically connected to an electronic memory, recording in the
electronic memory the plurality of coating thickness values, and recording
in the electronic memory a plurality of descriptive data units, each
descriptive data unit being associated with one of the coating thickness
values and defined, for example, with reference to an electronic pictorial
representation of the coated article. The steps of recording the coating
thickness values and of recording the descriptive data units may be
performed alternately.
Exemplary embodiments of the invention provide the on-site user with the
power of a personal computer together with an easy-to-use interface that
does not require a keyboard. Among other advantages, the gauge improves
the accuracy and reliability of coating thickness measurements, provides
the flexibility of plugging in any probe (e.g., magnetic, eddy current,
ultrasonic, etc.) to any PCMCIA-compatible device, and allows the user to
perform data analysis on-site.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, features and advantages of the present
invention will be more readily understood upon reading the following
detailed description in conjunction with the drawings in which:
FIG. 1 is a perspective view of a coating thickness gauge according to an
exemplary embodiment of the invention;
FIG. 2 is a schematic diagram of an exemplary PCMCIA card/probe unit;
FIG. 3a is an enlarged view of a portion of a first exemplary probe
assembly;
FIG. 3b is a diagram of a second exemplary probe assembly;
FIG. 4 is a schematic diagram of a portable computing unit;
FIG. 5 is a diagram of an exemplary control display on the portable
computing unit; and
FIG. 6 is a diagram of an exemplary output display on the portable
computing unit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a perspective view of a coating thickness gauge according to an
exemplary embodiment of the invention. The portable gauge 10 comprises a
probe 20 connected by a cable 30 to an interface unit 40 such as a
Personal Computer Memory Card International Association (PCMCIA) card. The
PCMCIA card 40 is adapted to communicate with a portable computing unit 50
via a port 60. The portable computing unit 50 is small enough to be held
comfortably in the palm of one's hand. However, it preferably includes a
relatively large screen display 70 to provide a graphical interface to the
user. The screen 70 is preferably, though not necessarily, a
touch-sensitive screen which can be activated, for example, with an index
finger or with any suitable pointed writing instrument 80. The portable
computing unit 50 can be of the type generally known as a Personal Digital
Assistant. The Apple NEWTON.RTM., which provides a graphical user
interface without a keyboard, is a preferred example of such a portable
computing unit 50.
The PCMCIA card 40 can be adapted to support a wide variety of peripheral
devices, and due to its versatility, allows virtually any type of probe 20
to be incorporated into the thickness gauge 10. For the purpose of
illustration, two exemplary embodiments will now be described briefly in
which a known type of probe 20 is implemented to measure the thickness of
a coating on substrate. However, those skilled in the art will recognized
that the PCMCIA card 40 can be adapted to support many other types of
probes 20 in conjunction with the portable computing unit 50.
According to one embodiment, as shown in FIG. 2 and as further described in
commonly owned U.S. Pat. No. 5,293,132, entitled "Coating Thickness
Measurement Gauge", which is hereby incorporated herein by reference, the
probe 20 of the coating thickness gauge 10 can be the inductor 75 of an LC
oscillator 85 of suitable, known type. The LC oscillator 85 allows for the
measurement of the thickness of an electrically nonconductive coating on
an electrically conductive substrate. The inductor 75 can be a simple
air-core solenoid-type coil. The phrase "air-core" is meant to refer to a
coil having a core made of nonmagnetic, nonmetallic material. In practice,
the wire is wound around a nonmagnetic, nonmetallic rod. During
measurement, a probe structure housing the probe is placed in contact with
the surface of the coating such that the separation of the coil 75 and the
electrically conductive substrate is a function of the geometry of the
probe structure and the coating thickness.
The impedance of the coil 75 varies with its proximity to the electrically
conductive substrate resulting in a corresponding variation in the
oscillation frequency of the LC oscillator 85. This frequency is
determined by a counter 90 which is used in conjunction with a
microprocessor 100. For instance, a timing loop may be programmed into the
microprocessor 100 such that it resets the counter 90 at the beginning of
the timing loop and measures the period of time elapsed until a
predetermined number of oscillations has occurred as indicated by an
overflow signal. The number of measured oscillations should be large
enough to achieve the desired accuracy.
The relationship of the change in frequency of the oscillator 85 to the
coating thickness is dependent on the particulars of the geometry of the
probe assembly 20, shown in expanded detail in FIG. 3a. The most
significant parameters affecting the relationship of the change in
frequency to the coating thickness are the diameter r of the coil 75, the
number of turns of the coil 75, the height I of the coil 75, the gauge of
the wire as it affects the dimension b, and the material of the wound
wire. Furthermore, the relationship is different depending on the material
composition of the substrate. For a nonmagnetic substrate such as
aluminum, the relationship may be approximated by the fourth-order
polynomial:
Y=A.sub.0 +A.sub.1 F+A.sub.2 F.sup.2 +A.sub.3 F.sup.3 +A.sub.4 F.sup.4
where the coefficients A.sub.0-4 are determined by the geometry of the
probe 20 and the electrical characteristics of the substrate.
For a six-turn single layer wound coil using 26-gauge copper wire, the
coefficients A.sub.0-4 may be empirically determined and represented as
follows for nonmagnetic aluminum substrates, with F representing the
frequency change in KHz and Y representing the thickness in microns:
Y=10090.44-(26.965)F+(3.0195.times.10.sup.-2)F.sup.2
-(1.60-374.times.10.sup.-5)F.sup.3 +(+3.25473.times.10.sup.-9)F.sup.4
A complete set of coefficients A.sub.0-4 can be stored in a ROM portion 110
associated with the microprocessor unit 100 during production of the
thickness 10 gauge for any desired substrate material. For example, an
additional set of coefficients B.sub.0-4 can be stored for use with
magnetic substrates. Thus, upon selection by the user of one of the
substrate materials stored in memory, the coefficients associated with the
selected substrate material can be recalled from the ROM 110 and employed
along with the measured frequency change in the appropriate equation shown
above for determining coating thickness.
According to a second exemplary embodiment, a second gauge probe can be
used in conjunction with the present invention to determine automatically,
with a single probe, the substrate characteristics, and to effect a
measurement of the coating thickness on that substrate. Such a probe is
described for example in commonly owned U.S. Pat. No. 5,343,146, entitled
"Combination Coating Thickness Gauge Using a Magnetic Flux Density Sensor
and an Eddy Current Search Coil", which is hereby incorporated herein by
reference. The probe tests for a ferrous substrate, measuring the
temperature-compensated magnetic flux density at a pole of a permanent
magnet using a Hall effect magnetic sensor and a thermistor. FIG. 3b shows
a probe 25 which includes a permanent magnet 35, a Hall effect magnetic
sensor 45, and a thermistor 55. The magnetic flux density and temperature
measurements are converted into a temperature-compensated magnetic flux
density value that is proportional to the coating thickness on the ferrous
substrate. If no ferrous substrate is detected, the coating thickness
gauge automatically switches over to test for a conductive nonferrous
substrate, measuring the effects of eddy currents generated in the
conductive nonferrous substrate by the coating thickness gauge magnetic
fields using an eddy current search coil 65, as shown in FIG. 3b. The eddy
current measurements are converted into an eddy current frequency value
that is proportional to the coating thickness on the conductive nonferrous
substrate.
Various other types of known probes may also be incorporated into the
present invention, for example probes which measure coating thicknesses on
ferrous substrates with a magnetic induction technique using two coils and
a ferrous core. As discussed with regard to the first embodiment, the
PCMCIA card 40 can be adapted to include hardware elements such as a
counter or a ROM chip to support a desired coating thickness gauge probe.
The gauge electronics 120 in FIG. 2 are thus intended to generally
represent a capacity of the PCMCIA card 40 to include hardware elements to
support any type of gauge probe. For example, as will be readily
appreciated by those skilled in the art, the PCMCIA card 40 can be
modified by one skilled in the art to include hardware to support probes
which measure thicknesses of nonmagnetic coatings on ferrous substrates,
nonconductive coatings on nonferrous substrates, combination probes which
measure both, or probes which ultrasonically measure coating thicknesses
on nonmetals.
In addition to the hardware support elements 120 included in the PCMCIA
card 40 for a particular application, The PCMCIA card 40 also includes the
microprocessor 100 and a PCMCIA interface 130 which creates a standardized
communication path from the microprocessor 100 to the portable computing
unit 50. Included in the PCMCIA interface 130 is a Universal Asynchronous
Receiver Transmitter (UART) 140, an I/O device which sends and receives
information in bit-serial fashion. The microprocessor 100, in conjunction
with the supporting hardware 120, converts the signal from the probe 20
into a digital representation of a coating thickness which is transmitted
through the UART 140 to the portable computing unit 50 in a standardized
PCMCIA format. For brevity, the details of this process are omitted, as
those skilled in the art are capable of adapting a particular signal to
the PCMCIA format.
The physical attributes and internal operation of the PCMCIA card 40 are
defined in detail by the Personal Computer Memory Card International
Association, which updates the PCMCIA specifications periodically. The
PCMCIA standard includes detailed specifications regarding the physical
attributes of the card such as dimensions and mechanical tolerances, card
interface information such as signal definitions for the connecting pins
125 of the PCMCIA card, and data organization on the card. Because the
PCMCIA card is a standard interface, the present invention provides a
versatile coating thickness gauge which can be used in a wide variety of
hardware environments.
The portable computing unit 50 receives the PCMCIA card 40 via a port 60 to
communicate with the probe 20. The portable computing unit 50 includes,
among other elements, a microprocessor 150 for controlling the operations
of the coating thickness gauge 10. See FIG. 4. The portable computing unit
50 can be programmed, for example, to automatically recognize the type of
probe which is connected to the portable computing unit 50. The
microprocessor 150 is associated with a memory 160 which can store
computer programs which control the operation of the gauge 10. The
microprocessor 150 exchanges data with the memory 160 and with the user
via the provide a graphics large enough to provide a graphical interface
for the user. The versatility provided by the memory 160, the
microprocessor 150, the large screen 70, and the standard PCMCIA interface
thus provide the coating thickness gauge 10 of the present invention with
many important advantages. Exemplary embodiments of the invention, for
example, provide the user with the ability to perform complete data
analysis or statistical process control on-site, the flexibility of using
any probe with any PCMCIA-compatible portable computing unit 50, and the
capability of providing a sophisticated user interface which allows the
user to easily annotate coating thickness measurements with descriptive
textual and graphical data.
According to one exemplary method of the invention, a user of the gauge 10
alternates between recording a thickness measurement reading with the
probe 20 and entering descriptive data via the screen 70. The descriptive
data can be entered in a number of ways. For example, a virtual typewriter
keyboard can be graphically simulated on the screen 70 for entry of
descriptive comments relating to a particular thickness measurement using
an index finger or a pointed writing instrument 80. Alternatively, the
portable computing unit 50 can be adapted to convert a handwritten image,
created by handwriting on the screen with the writing instrument 80, into
textual data. The process of converting a handwritten image of "electronic
ink" or typed letters into digital textual data, which has been
incorporated into the Apple NEWTON.RTM., greatly facilitates the entry of
descriptive data associated with a particular coating thickness
measurement. The ability to label all or selective individual data points
with descriptive text also enhances the reliability of the measured
coating thickness data by ensuring that data points are properly labeled
and by allowing the user to immediately record any abnormalities as
measurements are taken.
According to a further exemplary method, a two- or three-dimensional image
of the object to be measured can be created on the screen 70 by the user
as a reference for input coating thickness data points. According to this
method, a user first recalls or sketches a diagram of the object to be
measured on the screen 70 of the portable computing unit 50 using the
writing instrument 80. This process can be facilitated with a program,
included in the Apple NEWTON, which transforms user-created images into
various geometrical forms such as rectangles and circles. The drawing is
then stored in the memory 160 as a reference for the measured thickness
values. As coating thickness values are obtained with the probe 20, the
user identifies, with reference to the screen drawing, the locations on
the object at which the coating thickness values were obtained. In
addition, the user can input for any coating thickness value, a textual
description relating to the measured data point. FIG. 1 is an example
which depicts a drawing of a coated pipe 170 which a user would measure to
obtain coating thickness values at various locations. After taking a
measurement of the actual pipe with the probe 20, the user simply
indicates the location of the data point with reference to the pictorial
representation on the screen 70 using the writing instrument. The screen
thus serves as a graphical interface to record the location of data points
180, as shown in FIG. 1.
The large touch-sensitive screen 70 of the portable computing unit 50 can
be further adapted to facilitate operation of the coating thickness gauge
10 with a number of virtual buttons. As shown in FIG. 5, the screen 70 can
include several virtual buttons 190 which, for example, allow the user to
enter a memory mode to begin storing thickness measurements, enter high
and low tolerance limits, command the gauge to compute and display
statistics on the data thus obtained, enter parameters specifying a
particular process used in applying a coating, specify units for the
coating thickness readings, or any other desired function. The process
control button can be used for, among other functions, labeling any batch
with a particular process used in coating. This feature facilitates data
analysis by allowing the user to analyze a group of batches associated
with the same coating process. Calibration buttons 200 are provided to
calibrate the gauge when a reading differs from a known thickness.
At the top of the screen 70, a display section 210 may be provided which
displays thickness readings with units, an indicator of whether a ferrous
or nonferrous material was measured, a textual description of a particular
batch, and a label for a particular process used in coating. The screen 70
shown in FIG. 5 is of course intended to provide an example illustrating
the versatility of one embodiment of an exemplary coating thickness gauge.
It will be readily appreciated by those skilled in the art, however, that
many modifications in the screen interface can be affected without
departing from the scope of the invention.
The screen 70 can also be adapted to provide graphical output, which
advantageously allows the on-site user to use statistical process control
in analyzing coating thickness measurements. FIG. 6 shows an exemplary
output screen which includes graphs 220 and 230 of x-bar and range for a
set of batches, a histogram 240, and a list of desired statistics 250 for
the stored readings. The x-bar graph 220 shows on the screen 70 a computed
average thickness value for each batch. The range graph 230 shows a
computed difference in thickness between the greatest and least measured
thickness in a particular batch. These graphs thus allow the user to
easily monitor any anomalies or trends in the coating process. Moreover,
according to an exemplary embodiment of the invention, the user can access
any annotations or other descriptive data associated with a batch or
thickness measurement simply by touching the displayed batch number, data
point, or other indicia on the screen 70 with the writing instrument 80.
This capability allows the user to determine, for example, whether
anomalies illustrated in the output graphs are associated with any
anomalies described in annotations recorded during measurement.
The histogram 240 provides an additional visual indicator of the
consistency of recorded coating thickness measurements. The list of
statistics 250 can include, among other parameters, a standard deviation
calculated from measurements of selected batches, a maximum and a minimum
reading, upper and lower set limits (USL, LSL) set by the user, and upper
and lower control limits (UCL, LCL) which represent the average thickness
plus or minus three standard deviations. Like the screen of FIG. 5, the
output screen in FIG. 6 is, of course, intended to show one embodiment
which may be modified, for example, to accommodate other statistical
process control operations without departing from the scope of the
invention.
The present coating thickness gauge according to exemplary embodiments of
the invention thus provides many important advantages in obtaining coating
thickness measurement data. By combining a portable computing unit such as
a Personal Digital Assistant with a coating thickness gauge probe via a
PCMCIA interface, the invention greatly enhances the computing options
available for obtaining and processing coating thickness measurements
on-site. Thus, the user may perform data analysis, enter descriptive
comments, control the gauge with icons, and generally harness the power of
a large display, resident software, and regular upgrades of the portable
computing unit. Moreover, these advantages are provided in a coating
thickness gauge which is substantially less expensive to manufacture than
commercially available gauges.
The above-described exemplary embodiments are intended to be illustrative
in all respects, rather than restrictive, of the present invention. Thus
the present invention is capable of many variations in detailed
implementation that can be derived from the description contained herein
by a person skilled in the art. All such variations and modifications are
considered to be within the scope and spirit of the present invention as
defined by the following claims.
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