U.S. patent application number 09/779043 was filed with the patent office on 2001-08-16 for method for attenuating thermal sensation when handling objects at non-body temperature.
Invention is credited to Lewis, David Andrew, Mok, Lawrence Shungwei.
Application Number | 20010014390 09/779043 |
Document ID | / |
Family ID | 26725972 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010014390 |
Kind Code |
A1 |
Lewis, David Andrew ; et
al. |
August 16, 2001 |
Method for attenuating thermal sensation when handling objects at
non-body temperature
Abstract
A method for fabricating an object to attenuate thermal
sensation when handling the object at non-body temperature, and an
object fabricated in accord with the method. There is first
provided a substrate which has a first surface subject to handling.
There is then formed upon the first surface of the substrate a
coating. The coating has an optimal density, an optimal thermal
conductivity and an optimal thickness such that when the substrate
having the coating formed thereupon is equilibrated at a non-body
temperature differing from a body temperature and the coating is
subsequently contacted with a body at the body temperature during
handling, the temperature of the surface of the coating at a
contact point of the body with the coating changes precipitously to
a temperature near the body temperature and subsequently returns
towards the non-body temperature at a rate which permits handling
of the coating at the location of the first surface of the
substrate by the body with attenuated thermal sensation. The
coating simultaneously also minimally attenuates a steady state
thermal transfer with respect to the substrate in comparison with
an otherwise equivalent substrate absent the coating.
Inventors: |
Lewis, David Andrew;
(Carmel, NY) ; Mok, Lawrence Shungwei; (Brewster,
NY) |
Correspondence
Address: |
ALEK P. SZECSY
66B JANET DRIVE
POUGHKEEPSIE
NY
12603
US
|
Family ID: |
26725972 |
Appl. No.: |
09/779043 |
Filed: |
February 8, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09779043 |
Feb 8, 2001 |
|
|
|
08966168 |
Nov 7, 1997 |
|
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60048279 |
Jun 2, 1997 |
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Current U.S.
Class: |
428/332 ;
257/E23.08; 257/E23.101; 257/E23.11; 264/45.1; 427/243; 428/304.4;
428/318.4; 428/418; 428/425.8; 428/450; 428/461; 428/462 |
Current CPC
Class: |
H05K 5/02 20130101; Y10T
428/249987 20150401; H01L 2924/0002 20130101; Y10T 428/31504
20150401; Y10S 428/92 20130101; Y10T 428/31551 20150401; Y10T
428/31826 20150401; Y10T 428/249991 20150401; Y10T 428/31605
20150401; Y10T 428/31529 20150401; Y10T 428/31696 20150401; H01L
23/373 20130101; H01L 2924/00 20130101; Y10T 428/31511 20150401;
Y10T 428/24999 20150401; Y10T 428/31692 20150401; Y10T 428/249953
20150401; Y10T 428/31678 20150401; H01L 23/34 20130101; H01L
2924/0002 20130101; H01L 23/36 20130101; Y10T 428/31931 20150401;
Y10T 428/24997 20150401; Y10T 428/31663 20150401; Y10T 428/26
20150115 |
Class at
Publication: |
428/332 ;
428/318.4; 428/304.4; 428/418; 428/425.8; 428/450; 428/461;
428/462; 427/243; 264/45.1 |
International
Class: |
B32B 015/08; B05D
005/00; B32B 015/04; B32B 027/40 |
Claims
What is claimed is:
1. A method for fabricating an object comprising: providing a
substrate, the substrate having a first surface subject to
handling; forming upon the first surface of the substrate a
coating, where: the coating has an optimal density, an optimal
thermal conductivity and an optimal thickness such that when the
substrate having the coating formed thereupon is equilibrated at a
non-body temperature differing from a body temperature and the
coating is subsequently contacted with a body at the body
temperature during handling, the body experiences an attenuated
thermal sensation; and the coating simultaneously minimally
attenuates a steady state thermal transfer with respect to the
substrate in comparison with an otherwise equivalent substrate
absent the coating.
2. The method of claim 1 wherein upon contacting the coating with
the body at the body temperature during handling, the temperature
of the surface of the coating at a contact point of the body with
the coating changes precipitously to a temperature near the body
temperature and subsequently returns towards the non-body
temperature at a rate which permits handling of the substrate at
the location of the coating by the body with the attenuated thermal
sensation.
3. The method of claim 1 wherein the substrate is formed from a
first material chosen from the group of first materials consisting
of metals, metal alloys, metal oxides, unfilled plastics, filled
plastics, reinforced plastics and composites thereof.
4. The method of claim 1 wherein the coating is formed from a
second material having: a density of from about 0.05 to about 1.2
grams per cubic centimeter; a thermal conductivity of from about
0.02 to about 0.15 watts per meter-degree centigrade; and a
thickness of from about 0.1 to about 3 millimeters.
5. The method of claim 4 wherein the coating is formed from a
second material selected from the group of second materials
consisting of foamed polymer materials, hollow bead filled polymer
materials, and low density inorganic materials.
6. The method of claim 5 wherein the polymer materials from which
are formed the foamed polymer materials and the hollow bead filled
polymer materials are selected from the group of polymer materials
consisting of polyurethane polymer materials, epoxy polymer
materials, phenolic polymer materials, rubber polymer materials,
silicone polymer materials and polystyrene polymer materials.
7. The method of claim 1 wherein the coating is formed upon the
first surface of the substrate through a coating method selected
from the group of coating methods consisting of deposition coating
methods and in-situ coating methods.
8. The method of claim 1 wherein the object is chosen from the
group of objects consisting of handheld electronics products,
mobile electronics products, other electronics products, consumer
products, industrial products and medical instruments.
9. The method of claim 1 wherein the non-body temperature is
greater than the body temperature and the attenuated thermal
sensation is an attenuated heat sensation.
10. The method of claim 1 wherein the non-body temperature is less
that the body temperature and the attenuated thermal sensation is
an attenuated cold sensation.
11. An object fabricated in accord with the method of claim 1.
12. A method for fabricating an electronics product comprising:
providing an electronics product, the electronics product having a
first surface subject to handling; forming upon the first surface
of the electronics product a coating, where: the coating has an
optimal density, an optimal thermal conductivity and an optimal
thickness such that when the electronics product having the coating
formed thereupon is equilibrated at a non-body temperature
differing from a body temperature and the coating is subsequently
contacted with a body at the body temperature during handling, the
body experiences an attenuated thermal sensation; and the coating
simultaneously minimally attenuates a steady state thermal transfer
with respect to the electronics product in comparison with an
otherwise equivalent electronics product absent the coating.
13. The method of claim 12 wherein upon contacting the coating with
the body at the body temperature during handling, the temperature
of the surface of the coating at a contact point of the body with
the coating changes precipitously to a temperature near the body
temperature and subsequently returns towards the non-body
temperature at a rate which permits handling of the substrate at
the location of the coating by the body with the attenuated thermal
sensation.
14. The method of claim 12 wherein the first surface of the
electronics product is formed from a first material chosen from the
group of first materials consisting of metals, metal alloys, metal
oxides, unfilled plastics, filled plastics, reinforced plastics and
composites thereof.
15. The method of claim 12 wherein the first surface of the
electronics product is chosen from the group of electronics
products surfaces consisting of electronics enclosure volume case
surfaces, electronics enclosure volume keyboard surfaces and
electronics enclosure volume keypad surfaces.
16. The method of claim 12 wherein the coating is formed from a
second material having: a density of from about 0.05 to about 1.2
grams per cubic centimeter; a thermal conductivity of from about
0.02 to about 0.15 watts per meter-degree kelvin; and a thickness
of from about 0.1 to about 3 millimeters.
17. The method of claim 16 wherein the second material is selected
from the group of second materials consisting of foamed polymer
materials, hollow bead filled polymer materials, and low density
inorganic materials.
18. The method of claim 17 wherein the polymer materials from which
are formed the foamed polymer materials and the hollow bead filled
polymer materials are selected from the group of polymer materials
consisting of polyurethane polymer materials, epoxy polymer
materials, phenolic polymer materials, rubber polymer materials,
silicone polymer materials and polystyrene polymer materials.
19. The method of claim 12 wherein the electronics product is
chosen from the group of electronics products consisting of
handheld electronics products, mobile electronics products and
other electronics products.
20. An electronics product fabricated in accord with the method of
claim 12.
21. An object comprising: a substrate having a first surface; and a
coating formed upon the first surface of the substrate, the coating
being formed from a second material having: a density of from about
0.05 to about 1.2 grams per cubic centimeter; a thermal
conductivity of from about 0.02 to about 0.15 watts per
meter-degree centigrade; and a thickness of from about 0.1 to about
3.0 millimeters.
22. The object of claim 21 wherein the substrate is formed from a
first material chosen from the group of first materials consisting
of metals, metal alloys, metal oxides, unfilled plastics, filled
plastics, reinforced plastics and composites thereof.
23. The object of claim 21 wherein the coating is formed from a
second material selected from the group of second materials
consisting of foamed polymer materials, hollow bead filled organic
materials, and low density inorganic materials.
24. The object of claim 23 wherein the polymer materials from which
are formed the foamed polymer materials and the hollow bead filled
polymer materials are selected from the group of polymer materials
consisting of polyurethane polymer materials, epoxy polymer
materials, phenolic polymer materials, rubber polymer materials,
silicone polymer materials and polystyrene polymer materials.
25. The object of claim 21 wherein the object is chosen from the
group of objects consisting of handheld electronics products,
mobile electronics products, other electronics products, consumer
products, industrial products and medical instruments.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to methods for
preventing thermal sensations when handling objects at non-body
temperatures. More particularly, the present invention relates to
methods for attenuating hot and cold thermal sensations when
handling objects at non-body temperatures, while maintaining proper
heat transfer into or from those objects.
[0003] 2. Description of the Related Art
[0004] As the electrical power operating requirements within
handheld and mobile electronics products continues to increase and
the electronics enclosure volumes of handheld and mobile
electronics products continues to decrease, it has become
increasingly important within advanced handheld and mobile
electronics products to provide adequate means for efficiently
dissipating thermal loads which are generated in normal operation
of those advanced handheld and mobile electronics products.
[0005] Handheld and mobile electronics products which are
particularly susceptible to generating significant thermal loads
whose dissipation is required for proper operation of those
handheld and mobile electronics products typically include handheld
and mobile electronics products whose operation employs high power
microprocessor circuitry and/or high speed rigid disk drive
operation. Such handheld and mobile electronics products typically
include, but are not limited to, mobile computers and mobile data
communications systems. Efficient dissipation of thermal loads from
within electronics enclosure volumes of such electronics products
is particularly desirable since elevated temperatures within such
electronics enclosure volumes often facilitate premature
microprocessing electrical circuitry failure and/or rigid disk
drive electrical or mechanical failure.
[0006] In light of the continuing trend towards decreasing handheld
and mobile electronics products weights and decreasing handheld and
mobile electronics products electronics enclosure volumes, it is
atypical within advanced handheld and mobile electronics products
fabrication that active cooling means, such as fans, are employed
to fully dissipate thermal loads from within electronics enclosure
volumes within those advanced handheld and mobile electronics
products. Rather, thermal load dissipation from within electronics
enclosure volumes within handheld and mobile electronics products
is typically largely undertaken through passive means, such as
conduction, convection and radiation, while employing various
electronics enclosure volume surfaces of the electronics products
as surfaces through which thermal loads from within those
electronics enclosure volumes may be dissipated.
[0007] Typical electronics enclosure volume surfaces through which
thermal loads are dissipated within advanced handheld and mobile
electronics products include but are not limited to electronics
enclosure volume case surfaces, electronics enclosure volume
keyboard surfaces and electronics enclosure volume keypad surfaces.
The dissipation of thermal loads through such electronics enclosure
volume surfaces is often largely governed by the thermal
conductivity characteristics of a bulk material from which is
formed the electronics enclosure volume surface. Common bulk
materials which may be employed in forming electronics enclosure
volume surfaces which assure efficient dissipation of thermal loads
from within electronics enclosure volumes within handheld and
mobile electronics products include metals, such as but not limited
to aluminum, magnesium and alloys thereof, as well as several
polymer materials, such as but not limited to carbon fiber filled
polycarbonate polymer materials, acrylonitrile butadiene styrene
(ABS) polymer materials and blends thereof
[0008] Although it is thus common in the art of handheld and mobile
electronics products fabrication to employ electronics enclosure
volume surfaces as a means to dissipate thermal loads from within
electronics enclosure volumes incident to normal operation of those
electronics products, dissipation of thermal loads through
electronics enclosure volume surfaces within advanced handheld and
mobile electronics products is not entirely without problems within
advanced handheld and mobile electronics products fabrication.
[0009] With regard to handheld and mobile electronics products
which require dissipation of particularly high levels of thermal
power within exceedingly limited electronics enclosure volume
surface areas (ie: a thermal power dissipation of greater than
about 0.03 watts per square centimeter of electronics enclosure
surface area), electronics enclosure volume surfaces within those
advanced handheld and mobile electronics products may readily reach
temperatures of greater than about 60 degrees centigrade. Such
elevated temperatures detract from a normally desirable,
comfortable and safe operation of those handheld and mobile
electronics products.
[0010] It is thus desirable in the art of handheld and mobile
electronics products fabrication to provide methods and materials
through which may be fabricated handheld and mobile electronics
products which simultaneously exhibit: (1) efficient dissipation of
thermal loads through electronics enclosure volume surfaces of
those handheld and mobile electronics products when operating those
handheld and mobile electronics products, and (2) substantial
attenuation of heat sensation upon human contact of those
electronics enclosure volume surfaces when handling and operating
those handheld and mobile electronics products. It is towards these
seemingly contradictory goals that the present invention is most
specifically directed.
[0011] In a more general sense, the present invention is also
directed towards providing methods and materials through which may
be fabricated thermally conductive objects, such as but not limited
to handheld and mobile electronics products, as well as other
electronics products and non-electronics products, which
simultaneously exhibit: (1) efficient dissipation of thermal loads
into or from those thermally conductive objects through surfaces of
those thermally conductive objects; and (2) substantial attenuation
of thermal sensation upon contact of the surfaces of those
thermally conductive objects when handling and operating those
thermally conductive objects. It is towards these analogously
contradictory goals that the present invention is more generally
directed.
SUMMARY OF THE INVENTION
[0012] A first object of the present invention is to provide a
method for fabricating an object, and an object fabricated in
accord with the method, where the method provides for efficient
dissipation of a thermal load into or from the object through a
surface of the object.
[0013] A second object of the present invention is to provide a
method in accord with the first object of the present invention,
where there is simultaneously attenuated a thermal sensation when
contacting the surface of the object with a body when handling or
operating the object.
[0014] A third object of the present invention is to provide a
method in accord with the first object of the present invention or
the second object of the present invention, where the object is a
handheld or mobile electronics product.
[0015] A fourth object of the present invention is to provide a
method in accord with the first object of the present invention,
the second object of the present invention or the third object of
the present invention, which method is readily manufacturable.
[0016] In accord with the objects of the present invention, there
is provided by the present invention a method for fabricating an
object, and an object fabricated in accord with the method. To
practice the method of the present invention, there is first
provided a substrate having a first surface subject to handling.
There is then formed upon the first surface of the substrate a
coating. The coating has an optimally low density, an optimally low
thermal conductivity, an optimally low heat capacity and an
optimally minimal thickness such that when the substrate having the
coating formed thereupon is equilibrated at a non-body temperature
differing from a body temperature and the coating is subsequently
contacted with a body at the body temperature during handling, the
temperature of the surface of the coating at a contact point of the
body with the coating changes precipitously to a temperature near
the body temperature and subsequently partially returns towards the
non-body temperature at a rate which permits handling of the
substrate at the location of the coating by the body with
attenuated thermal sensation. In addition, the coating
simultaneously also minimally attenuates a steady state heat
transfer with respect to the substrate in comparison with an
otherwise equivalent substrate absent the coating.
[0017] The method of the present invention contemplates an object
fabricated in accord with the method of the present invention.
[0018] The present invention provides a method for fabricating an
object while: (1) providing an efficient thermal dissipation of a
thermal load into or from the object through a surface of the
object, while simultaneously; (2) attenuating a thermal sensation
when contacting the object in normal handling or operation of the
object through the surface of the object. The method of the present
invention realizes the foregoing objects by forming upon a first
surface of a substrate from which is formed an object a coating.
The first surface of the substrate is subject to handling. The
coating has an optimally low density, an optimally low thermal
conductivity, an optimally low heat capacity and an optimally
minimal thickness such that there is provided: (1) an efficient
thermal dissipation of a thermal load into or from the substrate at
the location of the coating, while simultaneously; (2) attenuating
a thermal sensation when contacting the coating by a body in normal
handling or operation of the substrate at the location of the
coating.
[0019] The method of the present invention may be employed where
the object is a handheld or mobile electronics product. The method
of the present invention does not discriminate with respect to the
nature of the object for which there may be simultaneously: (1)
provided an efficient thermal dissipation of a thermal load into or
from the object through a surface of the object, and; (2)
attenuated a thermal sensation when contacting the object with a
body in normal handling or operation of the object through the
surface of the object. Thus, although the method of the present
invention is most likely to provide value when simultaneously: (1)
providing an efficient thermal dissipation of a thermal load from
within a handheld or mobile electronics product electronics
enclosure volume through an electronics enclosure volume surface of
the handheld or mobile electronics product, and; (2) attenuating a
thermal sensation when contacting the handheld or mobile
electronics product electronics enclosure volume surface with a
body in normal handling or operation of the handheld or mobile
electronics product, the method of the present invention may also
be employed in fabricating objects other than handheld and mobile
electronics products. The method of the present invention may in
general be employed in fabricating objects including but not
limited to handheld electronics products, mobile electronics
products, other electronics products, consumer products, industrial
products and medical instruments.
[0020] The method of the present invention is readily
manufacturable. As is disclosed within the Description of the
Preferred Embodiment, methods and materials through which coatings
may be formed upon substrates with optimally low densities,
optimally low thermal conductivities, optimally low heat capacities
and optimally minimal thicknesses to realize the objects of the
present invention are accessible through coatings technology which
may be employed within at least handheld and mobile electronics
products electronics enclosure volume surface fabrication, and
presumable also other object fabrication. Thus, the method of the
present invention, and an object fabricated in accord with the
method of the present invention, is readily manufacturable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The objects, features and advantages of the present
invention are understood within the context of the Description of
the Preferred Embodiment, as set forth below. The Description of
the Preferred Embodiment is understood within the context of the
accompanying drawings, which form a material part of this
disclosure, wherein:
[0022] FIG. 1 shows a schematic cross-sectional diagram
illustrating steady state heat flow through a substrate in absence
of the present invention.
[0023] FIG. 2 shows a schematic cross-sectional diagram
illustrating transient heat flow through a substrate at non-body
temperature contacted with a body at body temperature in absence of
the present invention.
[0024] FIG. 3 shows a schematic cross-sectional diagram
illustrating steady state heat flow through a substrate having
formed thereupon a coating in accord with the present
invention.
[0025] FIG. 4 shows a schematic cross-sectional diagram
illustrating transient heat flow through a substrate at non-body
temperature, the substrate having formed thereupon a coating
contacted with a body at body temperature, at the time of contact
of the coating with the body, in accord with the present
invention.
[0026] FIG. 5 shows a schematic cross-sectional diagram
illustrating transient heat flow through a substrate at non-body
temperature, the substrate having formed thereupon a coating
contacted with a body at body temperature, at a time past the time
of contact of the coating with the body, in accord with the present
invention.
[0027] FIG. 6 shows a prophetic plot of Temperature versus Distance
for transient heat flow at progressive times through a substrate
formed of aluminum contacted with a body, in accord with the
schematic cross-sectional diagram of FIG. 2.
[0028] FIG. 7 shows a prophetic plot of Temperature versus Contact
Time at the various temperature measurement locations in accord
with the schematic cross-sectional diagram of FIG. 2, for transient
heat flow through the substrate formed of aluminum contacted with a
body, in accord with the schematic cross-sectional diagram of FIG.
2.
[0029] FIG. 8 shows a prophetic plot of Temperature versus Distance
for transient heat flow at progressive times through a substrate
formed of a polymer contacted with a body, in accord with the
schematic cross-sectional diagram of FIG. 2.
[0030] FIG. 9 shows a prophetic plot of Temperature versus Contact
Time at the various temperature measurement locations in accord
with the schematic cross-sectional diagram of FIG. 2, for transient
heat flow through the substrate formed of the polymer contacted
with a body, in accord with the schematic cross-sectional diagram
of FIG. 2.
[0031] FIG. 10 shows a prophetic plot of Temperature versus
Distance for transient heat flow at progressive times through a
substrate formed of a polymer having formed thereupon a coating
contacted with a body, in accord with the preferred embodiment of
the present invention, as illustrated within the schematic
cross-sectional diagrams of FIG. 4 and FIG. 5.
[0032] FIG. 11 shows a prophetic plot of Temperature versus Contact
Time at the various temperature measurement locations in accord
with the schematic cross-sectional diagrams of FIG. 4 and FIG. 5,
for transient heat flow through the substrate formed of the polymer
having formed thereupon the coating contacted with the body, in
accord with the preferred embodiment of the present invention, as
illustrated within the schematic cross-sectional diagrams of FIG. 4
and FIG. 5.
[0033] FIG. 12 shows a prophetic plot of Temperature versus Contact
Time at the various temperature measurement locations in accord
with the schematic cross-sectional diagrams of FIG. 4 and FIG. 5,
for transient heat flow through a substrate formed of aluminum
having formed thereupon a coating contacted with a body, the
coating having a first thermal conductivity in accord with the
preferred embodiment of the present invention, as illustrated
within the schematic cross-sectional diagrams of FIG. 4 and FIG.
5.
[0034] FIG. 13 shows a prophetic plot of Temperature versus Contact
Time at the various temperature measurement locations in accord
with the schematic cross-sectional diagrams of FIG. 4 and FIG. 5,
for transient heat flow through a substrate formed of aluminum
having formed thereupon a coating contacted with a body, the
coating having a second thermal conductivity in accord with the
preferred embodiment of the present invention, as illustrated
within the schematic cross-sectional diagrams of FIG. 4 and FIG.
5.
[0035] FIG. 14 shows a plot of Temperature versus Contact Time at a
point of contact of a body with a substrate formed of aluminum
having formed thereupon a coating in accord with the preferred
embodiment of the present invention.
[0036] FIG. 15 shows a plot of Temperature versus Contact Time at a
point of contact of a body with a substrate formed of aluminum
without having formed thereupon a coating in accord with the
preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] The present invention provides a method for fabricating an
object, such as but not limited to a handheld or mobile electronics
product, and an object fabricated in accord with the method, where
through the method there is formed the object which simultaneously:
(1) provides for efficient dissipation of a thermal load into or
from the object through a surface of the object, and; (2)
attenuates a thermal sensation when contacting the object in normal
handling or operation of the object through the surface of the
object. The method of the present invention realizes the foregoing
objects by forming upon a first surface of a substrate from which
is formed the object a coating. The first surface of the substrate
is subject to handling. The coating has an optimally low density,
an optimally low thermal conductivity, an optimally low heat
capacity and an optimally minimal thickness such that there is
simultaneously provided: (1) an efficient dissipation of a thermal
load into or from the substrate at the location of the coating; and
(2) an attenuated thermal sensation when handling the substrate at
the location of the coating in normal handling or operation of an
object fabricated from the substrate.
[0038] Although the preferred embodiment of the present invention
discloses the invention within the context of simultaneously
providing: (1) efficient thermal dissipation of a thermal load from
within an electronics enclosure volume of a handheld or mobile
electronics product through an electronics enclosure volume surface
of the handheld or mobile electronics product; and (2) an
attenuated heat sensation when contacting the handheld or mobile
electronics product in normal handling or operation of the handheld
or mobile electronics product through the electronics enclosure
volume surface, the method of the present invention may also be
employed when fabricating objects other than handheld and mobile
electronics products while simultaneously: (1) optimizing thermal
load dissipation into or from those objects; and (2) minimizing
thermal sensations when handling those objects.
[0039] In that regard, the method of the present invention may in
general be employed in fabricating objects including but not
limited to handheld electronics products, mobile electronics
products, other electronics products, consumer products, industrial
products and medical instruments. Consumer products and industrial
products may include, but are not limited to, toasters, sandwich
makers, hotplates and refrigerated products. Medical instruments
may include, but are not limited to, stethoscopes. Within the
general method of the present invention, there may be attenuated
either a hot thermal sensation or a cold thermal sensation when
contacting an object with a human body or other warm blooded body
when handling or operating the object, while simultaneously
minimally attenuating a steady state heat transfer with respect to
the object.
[0040] Referring now to FIG. 1, there is shown a schematic
cross-sectional diagram illustrating steady state heat flow through
a substrate from which may be fabricated a heat generating object
at non-body temperature, in absence of the present invention. Shown
in FIG. 1 is a substrate 10 of thickness Xc. Within FIG. 1, the
substrate 10 separates a high temperature region R1 from a low
temperature region R2, while the arrows emanating from the left and
terminating to the right within in FIG. 1 represent thermal heat
flow. There is also shown in FIG. 1: (1) a first temperature T1 at
a first temperature measurement location at the surface of the
substrate 10 adjacent the high temperature region R1; and (2) a
second temperature T2 at a second temperature measurement location
at the surface of the substrate 10 adjacent the low temperature
region R2.
[0041] Within the preferred embodiment of the present invention,
the substrate 10 is preferably an electronics products substrate
chosen from the group of electronics products substrates consisting
of electronics enclosure volume case substrates, electronics
enclosure volume keyboard substrates and electronics enclosure
volume keypad substrates. More preferably, the substrate 10 is an
electronics enclosure volume case substrate employed in fabricating
an electronics enclosure within a handheld or mobile electronics
product. Preferably, the electronics enclosure volume case
substrate has a thickness of from about 0.1 to about 3.0
millimeters. Within a general embodiment of the present invention,
the substrate 10 may be a substrate employed in fabricating any of
the other objects disclosed above, with an appropriate
thickness.
[0042] Within both the preferred embodiment of the present
invention and a general embodiment of the present invention, the
substrate 10 may be formed from a material chosen from the group of
materials including but not limited to metals, metal alloys, metal
oxides, unfilled plastics, filled plastics, reinforced plastics and
composites thereof Within both the preferred embodiment of the
present invention and a general embodiment of the present
invention, the substrate 10 is preferably formed of a material
which has a thermal conductivity of greater than about 0.3 watts
per meter-degree centigrade.
[0043] Within FIG. 1, the first temperature T1 at the first
temperature measurement location and the second temperature T2 at
the second temperature measurement location are related, under
steady state conditions, by equation 1, as follows. T1=q(Xc/kc)+T2
(1)
[0044]
[0045] Within equation 1, q equals the thermal flux incident upon
the first surface of the substrate 10 adjacent to the high
temperature region R1 and kc equals the thermal conductivity of the
material from which is formed the substrate 10. For a typical
thermal flux q incident upon the first surface of a substrate 10 of
thickness about 1.2 millimeters at about 250 watts per square
meter, there is typically observed: (1) a temperature differential
T1-T2 of less than about 0.002 degrees centigrade for a substrate
10 formed of an aluminum material having a thermal conductivity of
about 204 watts per meter-degree centigrade; and (2) a temperature
differential T1-T2 of about 2 degrees centigrade for a substrate 10
formed of a polymer material having a thermal conductivity of about
0.15 watts per meter-degree centigrade.
[0046] Referring now to FIG. 2, there is shown a schematic
cross-sectional diagram illustrating transient heat flow through
the substrate 10 initially at steady state heat flow in accord with
the schematic cross-sectional diagram of FIG. 1, but wherein the
second surface of the substrate 10 is contacted with a body 12 (ie:
a finger of a human body which is otherwise not shown).
[0047] Within FIG. 2, the contact point of the body 12 with second
surface of the substrate 10 represents a third temperature
measurement location at which there is measured a third temperature
T3, while the corresponding contact point of the second surface of
the substrate 10 with the body represents a specific second
temperature measurement location at which there is measured a
second temperature T2'. Within the preferred embodiment of the
present invention, as well as many general embodiments of the
present invention, the body 12 is typically a thermally conductive
body, and the body 12 typically provides a relatively large sink
for thermal flow through the substrate 10 in comparison with
thermal flow dissipation through thermal convection to the ambient
within the low temperature region R2 from the second surface of the
thermally conductive substrate 10. As is illustrated within the
schematic cross-sectional diagram of FIG. 2, lateral thermal flow
within the substrate 10 converges at the contact point of the body
12 with the second surface of the substrate 10, thus, a third
temperature T3 at the third temperature measurement location
typically rapidly approaches a second temperature T2' at the
specific second temperature measurement location on the second
surface of the substrate 10 when the body 12 contacts the second
surface of the substrate 10.
[0048] Although not illustrated within the schematic
cross-sectional diagram of FIG. 2, within the preferred embodiment
of the present invention, although not necessarily within a general
embodiment of the present invention, the temperature of the body 12
prior to contact with the second surface of the substrate 10 is
typically, although not necessarily always, lower than the
temperature within the first region R1 but greater than the
temperature within the second region R2.
[0049] A first temperature T1 at the first temperature measurement
location, a second temperature T2' at the specific second
temperature measurement location and a third temperature T3 at the
third temperature measurement location within the schematic
cross-sectional diagram of FIG. 2 may be determined as a function
of contact time of the body 12 with the second surface of the
substrate 10 through simultaneous solution of an appropriate series
of transient heat transfer equations through methods as are known
in the art of heat transfer. For an example of an appropriate
series of heat transfer equations, see J. P. Holman, Heat Transfer,
McGraw-Hill (New York: 1976), pp. 95-101, the teachings of which
are incorporated herein fully by reference. Within the preferred
embodiment of the present invention, and most general embodiments
of the present invention, simultaneous solution of the appropriate
series of heat transfer equations as a function of contact time of
the body 12 with the substrate 10 is typically not readily
analytically achievable. Rather, simultaneous solution of the
appropriate series of heat transfer equations is typically
undertaken through a finite element approximation, as is
conventional in the art of thermal transfer calculations, to
provide a first temperature profile of the first temperature T1 at
the first temperature measurement location, a second temperature
profile of the second temperature T2' at the specific second
temperature measurement location and a third temperature profile of
the third temperature T3 at the third temperature measurement
location as a function of a series of contact times of the body 12
with the second surface of the substrate 10.
[0050] A typical, but by no means exclusive, finite element
approximation method may also be found within J. P. Holman, Heat
Transfer, McGraw-Hill (New York: 1976), pp. 57-145.
[0051] Referring now to FIG. 3, there is shown a schematic
cross-sectional diagram illustrating steady state heat flow through
a substrate in accord with the preferred embodiment of the present
invention. Shown in FIG. 3 is a schematic cross-sectional diagram
of a substrate 10 otherwise equivalent to the substrate 10 whose
schematic cross-sectional diagram is illustrated in FIG. 1, but
wherein there is formed upon the second surface of the substrate 10
a coating 11 of thickness Xi.
[0052] Within the preferred embodiment of the present invention,
and a general embodiment of the present invention, the coating 11
has an optimally low density, an optimally low thermal
conductivity, an optimally low heat capacity and an optimally
minimal thickness Xi such that when the substrate 10 having the
coating 11 formed thereupon is equilibrated at a non-body
temperature with respect to the high temperature region R1,
differing from a body temperature of the body 12, and the coating
11 is subsequently contacted with the body 12 at the body
temperature during handling, the temperature of the surface of the
coating 11 at a contact point of the body 12 with the coating 11
changes precipitously to a temperature near the body temperature
and subsequently returns towards the non-body temperature at a rate
which permits handling of the substrate 10 at the location of the
coating 11 by the body 12 with minimal thermal sensation. In
addition, the coating 11 simultaneously also minimally attenuates a
steady state heat transfer with respect to the substrate 10 as
illustrated in FIG. 3 in comparison with the otherwise equivalent
substrate 10 absent the coating 11, as illustrated in FIG. 1.
[0053] Also shown within FIG. 3 is: (1) a fourth temperature T4 at
a fourth temperature measurement location at a newly formed
interface derived from the second surface of the substrate 10 with
the coating 11; and (2) a fifth temperature T5 at a fifth
temperature measurement location at the surface of the coating 11
adjacent the low temperature region R2.
[0054] The interrelationship between a first temperature TI at the
surface of the substrate 10 adjacent the high temperature region R1
and a fifth temperature T5 at the surface of the coating 11
adjacent the low temperature region R2 is defined under steady
state conditions by equation 2, as follows.
T1=q(Xc/kc+Xi/ki)+T5 (2)
[0055] Within equation 2, ki equals the thermal conductivity of a
material from which is formed the coating 11. Equation 2 follows
analogously from equation 1. Similarly with equation 1, equation 2
may readily be solved analytically.
[0056] Referring now to FIG. 4 and FIG. 5, there is shown a pair of
schematic cross-sectional diagrams illustrating transient heat flow
through the substrate 10 having the coating 11 formed upon its
second surface when the coating 11 is contacted with the body 12
under conditions otherwise equivalent to those employed within the
schematic cross-sectional diagram of FIG. 2, but wherein the body
12 contacts the coating 11 rather than the substrate 10. Shown in
FIG. 4 is a schematic cross-sectional diagram illustrating thermal
flow through the substrate 10 and the coating 11 immediately upon
contact of the coating 11 with the body 12, while within FIG. 5
there is shown a schematic cross-sectional diagram illustrating
thermal flow through the substrate 10 and the coating 11 at a later
time after contact of the coating 11 with the body 12. Within both
FIG. 4 and FIG. 5, there is also defined: (1) a sixth temperature
T6 at a sixth temperature measurement location at the point of
contact of the body 12 with the coating 11; and (2) a fifth
temperature T5' at a specific fifth temperature measurement
location at a point of contact of the coating 11 with the body
12.
[0057] As is shown in FIG. 4, immediately upon contact of the body
12 with the coating 11, only a small amount of thermal flux flows
into the body 12 when the surface of the coating 11 is contacted
with the body 12. As is also shown in FIG. 4, the steady state
thermal flow through the substrate 10 and the coating 11 remains
otherwise largely unchanged.
[0058] As is shown in FIG. 5, at a somewhat later time after
contact of the body 12 with the coating 11, a somewhat larger, but
still substantially attenuated, thermal flux flows into the body
12. The substantially attenuated thermal flow as illustrated in
FIG. 5 typically provides a slight rise in the sixth temperature T6
at the sixth temperature measurement location, with an attenuated
if not minimal thermal heat sensation within the body 12. The
somewhat larger thermal flux flowing into the body 12 as
illustrated in FIG. 5 in comparison with FIG. 4 derives from a
slightly redirected thermal flow through the coating 11
concentrated and focused towards the contact point of the body 12
with the coating 11, as illustrated in FIG. 5.
[0059] Within the schematic cross-sectional diagrams of FIG. 4 and
FIG. 5, the first temperature T1 at the first temperature
measurement location, the fourth temperature T4 at the fourth
temperature measurement location, the fifth temperature T5' at the
specific fifth temperature measurement location and the sixth
temperature T6 at the sixth temperature measurement location may be
determined as a function of contact time of the body 12 with the
coating 11 by simultaneous solution of an appropriate second series
of heat transfer equations analogous to the series of heat transfer
equations whose simultaneous solution is employed in determining
the first temperature T1 at the first temperature measurement
location, the second temperature T2' at the specific second
temperature measurement location and the third temperature T3 at
the third temperature measurement location within the schematic
cross-sectional diagram of FIG. 2, as discussed above. Similarly,
the appropriate second series of heat transfer equations is also
not readily analytically simultaneously solved, and is typically
solved simultaneously through a finite element approximation
analogous or equivalent to the finite element approximation
employed in solving for the first temperature T1 at the first
temperature measurement location, the second temperature T2' at the
specific second temperature measurement location and the third
temperature T3 at the third temperature measurement location as a
function of body 12 contact time with the thermally conductive
substrate 10 as illustrated in FIG. 2.
[0060] As noted above, the coating 11 provides the desirable
attenuated thermal sensation to the substrate 10 and simultaneously
minimally attenuates steady state thermal transfer with respect to
the substrate 10 through choice of an optimally low density, an
optimally low thermal conductivity, an optimally low heat capacity
and an optimally minimal thickness when forming the coating 11.
[0061] With respect to the optimally low density of the coating 11,
for both the present invention and the preferred embodiment of the
present invention the optimally low density of the coating 11
provides minimal thermal flow into the body 12 when the body 12
contacts the surface of the coating 11. Within the present
invention and the preferred embodiment of the present invention,
the coating 11 preferably has a low density of from about 0.05 to
about 1.2 grams per cubic centimeter. More preferably, the coating
11 has a density of from about 0.05 to about 0.2 grams per cubic
centimeter. Most preferably, the coating 11 has a density of from
about 0.075 to about 0.1 grams per cubic centimeter.
[0062] Similarly, within the present invention and the preferred
embodiment of the present invention, the optimally low thermal
conductivity of the coating 11 provides a barrier to substantial
lateral thermal flow through either the substrate 10 or the coating
11 to the contact point of the surface of the coating 11 with the
body 12. Preferably, the coating 11 is formed of a material having
a low thermal conductivity of from about 0.02 to about 0.15 watts
per meter-degree centigrade. More preferably, the coating 11 is
formed from a material having a thermal conductivity of from about
0.03 to about 0.08 watts per meter-degree centigrade. Most
preferably, the coating 11 is formed from a material having a
thermal conductivity of from about 0.03 to about 0.06 watts per
meter-degree centigrade.
[0063] Finally, within the present invention and the preferred
embodiment of the present invention, the coating 11 is formed with
an optimally minimal thickness such that there is avoided within
the present invention and the preferred embodiment of the present
invention a thermal punch-through effect from the substrate 10
through the coating 11 to the contact point of the coating 11 with
the body 12. Preferably, the thickness of the coating 11 is from
about 0.1 to about 3.0 millimeters. More preferably, the thickness
of the coating 11 is from about 0.3 to about 1.0 millimeters. Most
preferably, the thickness of the thermally insulating coating 11 is
from about 0.4 to about 0.7 millimeters.
[0064] The final parameter of the coating 11 which is relevant to
the present invention but is not usually controllable within a
particularly large range is the heat capacity of the coating.
Within the present invention and the preferred embodiment of the
present invention, the coating 11 preferably has a heat capacity of
from about 0.70 to about 1.15 joules per gram per degree
centigrade. More preferably, the coating 11 has a heat capacity of
from about 0.85 to about 1.00 joules per gram per degree
centigrade. Most preferably, the coating 11 has a heat capacity of
from about 0.85 to about 0.95 joules per gram per degree
centigrade.
[0065] The foregoing preferred, more preferred and most preferred
limits for the density, the thermal conductivity, the thickness and
the heat capacity of the coating 11 within both the present
invention and the preferred embodiment of the present invention are
predicated upon a high temperature region R1 temperature of from
about 45 to about 120 degrees centigrade, a low temperature region
R2 temperature of from about 0 to about 40 degrees centigrade and a
body 12 temperature of from about 30 to about 39 degrees
centigrade. Significant variations within the above temperatures,
particularly with respect to the high temperature region R1
temperature and the low temperature region R2 temperature, may
require additional variations within the density, the heat capacity
and, particularly, the thickness, of the coating 11.
[0066] With respect to the materials from which may be formed the
coating 11, the coating 11 may be formed from materials including
but not limited to foamed polymer materials, hollow bead filled
polymer materials, and low density inorganic materials. The polymer
materials from which may be formed the foamed polymer materials and
the hollow bead filled polymer materials may be selected from the
group of polymer materials including but not limited to
polyurethane polymer materials, epoxy polymer materials, phenolic
polymer materials, rubber polymer materials, silicone polymer
materials and polystyrene polymer materials. The low density
inorganic materials may include, but are not limited to highly
porous glasses and ceramics, such as may be formed through aero
sol-gels, as well as highly porous metals and metal oxides. Within
the preferred embodiment of the present invention foamed
polyurethane polymer materials are preferred for forming the
coating 11.
[0067] Similarly, the coating 11 may be formed upon the substrate
10 through any of several coating methods as are generally known in
the art. Such coating methods may include, but are not limited to,
deposition coating methods, such as but not limited to roll coating
methods, spray coating methods, brush coating methods, laminating
methods (with or without added adhesive layers), casting methods,
injection molding methods, electrophoretic coating methods, powder
coating methods and dip coating methods employing solvents,
diluents, coloring agents, reinforcing agents and other additive
agents as are desirable to provide other properties within the
coating 11. Such other properties may include, but are not limited
to coloration properties, toughness properties, crack resistance
properties and abrasion resistance properties. Similarly, the
coating 11 may also be formed through in-situ coating methods such
as but not limited to chemically selective subtractive etching
methods, physically selective subtractive etching methods,
selective chemical growth methods, selective physical growth
methods and aggregate methods thereof, which employ modification of
the material from which is formed the substrate 10. Such aggregate
methods may include, for example and without limitation, a
selective subtractive etching of an metallic alloy substrate and
subsequent oxidation of the etched metallic alloy substrate to form
a highly porous metal oxide coating upon the metallic alloy
substrate.
[0068] Finally, although not specifically illustrated in FIG. 4 or
FIG. 5, the coating 11 may also have formed upon its surface
additional coatings which provide additional properties to an
object which is formed employing the coating 11. Such additional
coatings may be thermally insulating coatings or thermally
conductive coatings, while still preserving, at least in part, the
thermal barrier properties of the coating 11.
EXAMPLES 1-5
[0069] In order to prophetically illustrate the value of the
present invention in attenuating thermal sensation when handling an
object while simultaneously minimally attenuating steady state
thermal transfer with respect to the object, there was solved
through a finite element approximation method, as is conventional
in the art of heat transfer calculation, the values of a first
temperature T1 at a first measurement location, a second
temperature T2' at a specific second temperature measurement
location and a third temperature T3 at a third measurement location
of a substrate or a body, such as the substrate 10 and the body 12
as illustrated within the schematic cross-sectional diagram of FIG.
2, as a function of contact time of the body with the substrate, in
accord with transient heat flow equations as are conventional in
the art of heat transfer.
[0070] Illustrated in FIG. 6 is a plot of Temperature versus
Distance encompassing the second temperature T2' at the specific
second temperature measurement location and the third temperature
T3 at the third temperature measurement location resulting from
transient heat flow at progressive times through the surface of a
substrate formed of aluminum when contacted with a body in accord
with the schematic cross-sectional diagram of FIG. 2. In obtaining
the plot of FIG. 6, there was assumed: (1) an aluminum substrate
thickness of 1.2 mm; (2) an aluminum substrate density of 2.707
grams per cubic centimeter; and (3) an aluminum substrate thermal
conductivity of 204 watts per meter-degree centigrade. The density
and thermal conductivity of the body were assumed to be equivalent
to water, without convection, and the body was assumed to be an
infinite sink for thermal flux flow. Similarly, there was also
assumed a high temperature within a high temperature region, such
as the high temperature region R1 illustrated in FIG. 2, of 62
degrees centigrade, a low temperature within a low temperature
region, such as the low temperature region R2 illustrated in FIG.
2, of 25 degrees centigrade and a body temperature of 36 degrees
centigrade.
[0071] Shown in the plot of FIG. 6 is the temperature profile
through the substrate and into the body for the contact times of
t=0 milliseconds and t=39 milliseconds, along with several
intervening curves. Also illustrated is the location of measurement
of the second temperature T2' at the specific second temperature
measurement location and the third temperature T3 at the third
temperature measurement location. The contact times begin with a
contact time equal to zero (ie: t=0) and end with a contact time
equal to 39 milliseconds (ie: t=39). As is illustrated within the
plot of FIG. 6, the third temperature T3 at the third temperature
measurement location increases substantially within a short time
period of less than 39 milliseconds, as can be seen more clearly in
FIG. 7.
[0072] Shown in FIG. 7 is a plot of Temperature versus Contact Time
for the first temperature T1 at the first temperature measurement
location, the second temperature T2' at the specific second
temperature measurement location and the third temperature T3 at
the third temperature measurement location, in accord with the
schematic cross-sectional diagram of FIG. 2, for transient heat
flow through the substrate formed of aluminum in accord with the
parameters employed in calculating the curves illustrated within
FIG. 6. As is seen from the plot of FIG. 7, neither the first
temperature T1 at the first temperature measurement location, nor
the second temperature T2' at the specific second temperature
measurement location decreases appreciably from a steady state
temperature, but the third temperature T3 at the third temperature
measurement location that corresponds to the temperature of the
body at the point of contact with the substrate increases
substantially within the short time period of about 39
milliseconds.
[0073] Referring now to FIG. 8, there is shown a plot of
Temperature versus Distance encompassing the second temperature T2'
at the specific second temperature measurement location and the
third temperature T3 at the third temperature measurement location
resulting from transient heat flow at progressive times through the
surface of a substrate formed of a polymer when contacted with a
body in accord with the schematic cross-sectional diagram of FIG.
2. The plot of FIG. 8 follows analogously from the plot of FIG. 6,
with the exception that there is employed within the plot of FIG. 8
a substrate formed of a polymer rather than of aluminum. In
obtaining the plot of FIG. 6, there was assumed: (1) a polymer
substrate thickness of 1.2 mm; (2) a polymer substrate density of
1.200 grams per cubic centimeter; and (3) a polymer substrate
thermal conductivity of 0.15 watts per meter-degree centigrade,
while still employing a density and thermal conductivity of the
body as equivalent to water, without convection. Similarly with the
plot of FIG. 6, there is observed within the plot of FIG. 8 a
substantial increase in the third temperature T3 at the third
temperature measurement location as a function of contact time of
the body with the substrate formed of the polymer within a
comparatively short contact timescale of about 39 milliseconds. In
contrast with the plot of FIG. 6, there is also observed within the
plot of FIG. 8 a substantial decrease of the second temperature T2'
at the specific second temperature measurement location as a
function of contact time of the body with the substrate formed of
the polymer within the comparatively short contact timescale of
about 39 milliseconds.
[0074] Referring now to FIG. 9, there is shown a plot of
Temperature versus Contact Time for the first temperature T I at
the first temperature measurement location, the second temperature
T2' at the specific second temperature measurement location and the
third temperature T3 at the third temperature measurement location
in accord with the schematic cross-sectional diagram of FIG. 2, for
transient heat flow through the substrate formed of the polymer, in
accord with the plot of FIG. 8. As is seen from the
temperature-contact time profile curves within FIG. 9, the plot of
FIG. 9 corresponds with the plot of FIG. 7 insofar as there exists
a minimal decrease in the first temperature T1 at the first
temperature measurement location. There is, however, a substantial
decrease of the second temperature T2 at the second temperature
measurement location and a less substantial increase in the third
temperature T3 at the third temperature measurement location within
the comparatively short time interval of about 39 milliseconds
contact of the body with the substrate formed of the polymer in
comparison with the corresponding temperature-contact time profile
curves within FIG. 7.
[0075] Referring now to FIG. 10 there is shown a plot of
Temperature versus Distance for transient heat flow at progressive
times through a substrate formed of a polymer having formed
thereupon a coating in accord with the preferred embodiment of the
present invention, as illustrated within the schematic diagrams of
FIG. 4 and FIG. 5. The structure employed in calculating the
temperature profile curves as illustrated in FIG. 10 is otherwise
equivalent to the structure employed in calculating the temperature
profile curves of FIG. 8, with the exception that there is formed
upon the substrate formed of the polymer a coating.
[0076] In order to obtain the temperature profile curves within the
plot of FIG. 10, there was employed a finite element approximation
method analogous or equivalent to the finite element approximation
method employed in solving for the first temperature T1 at the
first temperature measurement location, the second temperature T2'
at the specific second temperature measurement location and the
third temperature T3 at the third temperature measurement location
within the plots of FIG. 6 to FIG. 9. Through the finite element
approximation method, there was calculated the first temperature T1
at the first temperature measurement location, the fourth
temperature T4 at the fourth temperature measurement location, the
fifth temperature T5' at the specific fifth temperature measurement
location and the sixth temperature T6 at the sixth temperature
measurement location, as illustrated in FIG. 4 and FIG. 5, as a
function of a contact time of a body, such as the body 12 as
illustrated in FIG. 4 and FIG. 5, with the coating, such as the
coating 11 as illustrated in FIG. 4 and FIG. 5. Within the finite
element approximation method, the coating was assumed to have a
density of 0.050 grams per cubic centimeter, a thermal conductivity
of 0.02 watts per meter-degree centigrade, a heat capacity of about
1.0 joules per gram per degree centigrade and a thickness of 0.3
millimeters.
[0077] In contrast with the temperature profile plots of FIG. 6 and
FIG. 8, within the temperature profile plot of FIG. 10 there is no
substantial increase of the sixth temperature T6 at the sixth
temperature measurement location (which corresponds with the third
temperature T3 at the third temperature measurement location within
FIG. 6 and FIG. 8), but rather there is a substantial decrease in
the fifth temperature T5' at the specific fifth temperature
measurement location (which corresponds with the second temperature
T2' at the specific second temperature measurement location within
FIG. 6 and FIG. 8).
[0078] Referring now to FIG. 11, there is shown a plot of
Temperature versus Contact Time for the first temperature T1 at the
first temperature measurement location, the fourth temperature T4
at the fourth temperature measurement location, the fifth
temperature T5' at the specific fifth temperature measurement
location and the sixth temperature T6 at the sixth temperature
measurement location in accord with the schematic cross-sectional
diagrams of FIG. 4 and FIG. 5, for transient heat flow through the
substrate formed of the polymer having formed thereupon the coating
in accord with the preferred embodiment of the present invention.
FIG. 11 corresponds, in general, with the temperature-contact time
plots as illustrated in FIG. 7 and FIG. 9, with the exception that
there is now added a temperature-contact time profile curve for the
fourth temperature T4 at the fourth temperature measurement
location.
[0079] As is shown in FIG. 11, the sixth temperature T6 at the
sixth temperature measurement location increases towards the first
temperature T I at the first temperature measurement location at a
rate substantially attenuated in comparison with the rate of
increase of the third temperature T3 at the third temperature
measurement location within the temperature-contact time profiles
of FIG. 7 and FIG. 9.
[0080] Referring now to FIG. 12, there is shown a plot of
Temperature versus Contact Time for the first temperature T1 at the
first temperature measurement location, the fourth temperature T4
at the fourth temperature measurement location, the fifth
temperature T5' at the specific fifth temperature measurement
location and the sixth temperature T6 at the sixth temperature
measurement location in accord with the schematic cross-sectional
diagrams of FIG. 4 and FIG. 5, for transient heat flow through a
substrate otherwise equivalent to the substrate employed in
providing the temperature-contact time plot of FIG. 11, but wherein
the substrate is a substrate formed of aluminum rather than a
substrate formed of a polymer.
[0081] Similarly, referring now to FIG. 13, there is shown a plot
of Temperature versus Contact Time for the first temperature T1 at
the first temperature measurement location, the fourth temperature
T4 at the fourth temperature measurement location, the fifth
temperature T5' at the specific fifth temperature measurement
location and the sixth temperature T6 at the sixth temperature
measurement location in accord with the schematic cross-sectional
diagrams of FIG. 4 and FIG. 5, for transient heat flow through a
substrate formed of aluminum having formed thereupon a coating
otherwise equivalent to the coating employed in determining the
plot of FIG. 12, but wherein the coating has a thermal conductivity
of 0.06 watts per meter-degree centigrade rather than a thermal
conductivity of 0.02 watts per meter-degree centigrade.
[0082] As is seen from review of the temperature-contact time
curves within the plots of FIG. 12 and FIG. 13, the trends in
temperature-contact time profiles of the first temperature T1 at
the first temperature measurement location, the fourth temperature
T4 at the fourth temperature measurement location, the fifth
temperature T5' at the specific fifth temperature measurement
location and the sixth temperature T6 at the sixth temperature
measurement location correspond with the trends in
temperature-contact time profiles of the first temperature T1 at
the first temperature measurement location, the fourth temperature
T4 at the fourth temperature measurement location, the fifth
temperature T5' at the specific fifth temperature measurement
location and the sixth temperature T6 at the sixth temperature
measurement location, as illustrated in FIG. 11. In particular with
respect to temperature-contact time profile of the sixth
temperature T6 at the sixth temperature measurement location within
FIG. 11, FIG. 12 and FIG. 13, the minimal rise in the sixth
temperature T6 at the sixth temperature measurement location as a
function of time may be employed to provide an object through which
there is obtained minimal thermal sensation by a body when
contacting the object.
[0083] In order to determine steady state heat transfer attenuation
of the thermally conductive substrate structures whose
temperature-contact time profiles are illustrated in FIG. 7, FIG.
9. FIG. 11, FIG. 12 and FIG. 13 there may be calculated the
appropriate temperature differentials T1-T2 or T1-T5, through use
of equation 1 or equation 2, as appropriate for individual
substrate structures. Such temperature differentials are readily
calculated and are presented in Table I, for a thermal flux of 250
watts per square meter.
1TABLE I Example Substrate Structure S/S Temp. Diff. 1 1.2 mm Al
<0.002 C 2 1.2 mm poly 2 3 1.2 mm poly/0.3 mm ctg (ki = 0.02)
5.8 4 1.2 mm Al/0.3 mm ctg (ki = 0.02) 3.8 5 1.2 mm Al/0.3 mm ctg
(ki = 0.06) 1.3
[0084] It is seen from review of the data in Table I that there
exists a minimal attenuation of steady state thermal transfer with
respect to a substrate, as evidenced by a minimally increased
temperature differential through the thickness of the substrate,
when the substrate has formed thereupon a coating in accord with
the preferred embodiment of the present invention.
EXAMPLES 6-7
[0085] There was obtained an aluminum sheet of thickness about 1.2
mm and thermal conductivity of about 204 watts per meter-degree
centigrade. There was then formed upon the aluminum sheet a foamed
urethane organic coating having dispersed therein a carbon black
pigment at a loading of about 2 weight percent. The foamed urethane
coating was formed from a urethane material foamed with water which
upon reaction formed a carbon dioxide foamed urethane coating
having a density of about 0.3 grams per cubic centimeter, a thermal
conductivity of about 0.05 watts per meter-degree centigrade, a
heat capacity of about 0.93 joules per gram per degree centigrade
and a thickness of about 0.6 millimeters upon one side of the
aluminum sheet.
[0086] The side of the aluminum sheet without the foamed urethane
coating formed thereupon was then placed in contact with a
precisely heated aluminum block and maintained at a temperature of
about 60 degrees centigrade. Steady state temperatures of the side
of the aluminum sheet in contact with the aluminum block and the
exposed surface of the foamed urethane coating were obtained
employing 42 gauge thermocouple wire which provided minimal
additional thermal dissipation and determined to be about 60
degrees centigrade for the side of the aluminum sheet in contact
with the aluminum block and about 57 degrees centigrade for the
surface of the foamed urethane coating.
[0087] The thermocouple contacting the foamed urethane coating was
then contacted with a finger of a human body at a temperature of
about 32 degrees centigrade, where the body provided substantial
thermal dissipation in comparison with the thermocouple. The
thermocouple contacting the back side of the aluminum sheet in
contact with the aluminum block measured a constant temperature of
about 60 degrees centigrade, while the thermocouple contacting the
foamed urethane coating measured a temperature which decreased
precipitously to a temperature of about 37 degrees centigrade upon
body contact with the thermocouple and subsequently rose slightly
at an initial approximately linear rate of about 10 degrees
centigrade per minute to reach a plateau of about 42 degrees
centigrade in a time period of about 30 seconds. A plot of
Temperature versus Contact Time for the thermocouple contacted
region of the foamed urethane coating is shown in FIG. 14, where
the discontinuity beginning at about 2.5 seconds indicates body
contact with the thermocouple.
[0088] For comparison purposes, a plot of Temperature versus
Contact Time for a thermocouple contacted region of an otherwise
equivalent aluminum substrate absent the foamed urethane coating is
shown in FIG. 15. As is shown in FIG. 15, upon body contact with
the thermocouple at about 2.5 seconds, the temperature measured by
the thermocouple decreased precipitously to a temperature
substantially above the body temperature and rapidly returned to
the aluminum substrate temperature in less than about 20
seconds.
[0089] Thus, consistent with examples 1-5, it is seen from examples
6-7 that there may in practice be formed an object from a substrate
having a coating formed thereupon, where the coating permits
handling of the object with attenuated thermal sensation while
simultaneously minimally attenuating a steady state thermal
transfer with respect to the object in comparison with an otherwise
equivalent object absent the coating.
[0090] As is understood by a person skilled in the art, the
preferred embodiment and examples of the present invention are
illustrative of the present invention rather than limiting of the
present invention. Modifications and revisions may be made to
materials, structures and dimensions through which is fabricated an
object in accord with the preferred embodiment and examples of the
present invention, while still providing an embodiment or example
of an object in accord with the present invention, as defined by
the appended claims.
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