U.S. patent application number 09/853601 was filed with the patent office on 2001-11-01 for system and method for removing liquid from rear window of vehicle.
This patent application is currently assigned to Guardian Industries Corporation. Invention is credited to Pike, Ryan E., Veerasamy, Vijayen S..
Application Number | 20010035662 09/853601 |
Document ID | / |
Family ID | 24040609 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010035662 |
Kind Code |
A1 |
Pike, Ryan E. ; et
al. |
November 1, 2001 |
System and method for removing liquid from rear window of
vehicle
Abstract
A system and method for efficiently removing rain water and the
like from a rear window (backlite) of a vehicle. A rear spoiler or
air deflector is provided for redirecting air toward the backlite
and causing the speed of air flow to increase. A hydrophobic
coating is provided on the major exterior surface of the backlite.
Air directed by the air deflector over and/or across the surface of
the backlite functions to remove the rain water and the like from
the backlite. In certain embodiments, the hydrophobic coating may
include diamond-like carbon (DLC) deposited on the substrate in a
manner to increase its hydrophobicity.
Inventors: |
Pike, Ryan E.; (Rochester
Hills, MI) ; Veerasamy, Vijayen S.; (Farmington
Hills, MI) |
Correspondence
Address: |
Nixon & Vanderhye P.C.
1100 N. Glebe Rd., 8th Floor
Arlington
VA
22201
US
|
Assignee: |
Guardian Industries
Corporation
|
Family ID: |
24040609 |
Appl. No.: |
09/853601 |
Filed: |
May 14, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09853601 |
May 14, 2001 |
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09512798 |
Feb 25, 2000 |
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6273488 |
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09512798 |
Feb 25, 2000 |
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09303548 |
May 3, 1999 |
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6261693 |
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09512798 |
Feb 25, 2000 |
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09442805 |
Nov 18, 1999 |
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Current U.S.
Class: |
296/91 ;
296/180.1 |
Current CPC
Class: |
B60J 1/2008 20130101;
B60S 1/58 20130101; B32B 17/10577 20130101; C03C 17/3634 20130101;
C03C 3/076 20130101; C03C 2217/282 20130101; C03C 17/36 20130101;
C03C 23/0075 20130101; B32B 17/1033 20130101; C03C 17/22 20130101;
B62D 35/007 20130101; Y02T 10/82 20130101; C03C 17/3652 20130101;
C03C 2217/76 20130101; C03C 17/3441 20130101; B60S 1/54 20130101;
B05D 5/083 20130101; C03C 17/366 20130101; B08B 17/065 20130101;
C03C 2218/31 20130101; B32B 17/10018 20130101; B08B 17/06 20130101;
C03C 2218/151 20130101; C03C 17/3644 20130101 |
Class at
Publication: |
296/91 ;
296/180.1 |
International
Class: |
B60J 001/20 |
Claims
We claim:
1. A system for enabling rain water to be removed from an exterior
surface of a backlite of a vehicle, said system comprising: an air
deflector for redirecting air from flowing in a first direction
across a surface of the vehicle to a second direction in which air
flows downwardly toward the backlite, and for causing at least a
portion of the air flowing the second direction to flow faster than
air in the first direction; and wherein said backlite includes a
substrate with a hydrophobic coating thereon, so that the exterior
surface of the backlite has an initial contact angle .theta. of at
least about 70 degrees.
2. The system of claim 1, wherein said substrate is a glass
substrate comprising, on a weight basis: SiO.sub.2 from about
60-80%, Na.sub.2O from about 10-20%, CaO from about 0-16%, K.sub.2O
from about 0-10%, MgO from about 0-10%, Al.sub.2O.sub.3 from about
0-5%; and wherein said hydrophobic coating includes diamond-like
carbon (DLC) having sp.sup.3 carbon-carbon bonds; and wherein said
hydrophobic coating has an initial contact angle .theta. with a
sessile drop of water thereon of at least about 100 degrees, and an
average hardness of at least about 10 GPa.
3. The system of claim 1, wherein said initial contact angle is at
least about 110 degrees.
4. The system of claim 2, wherein said initial contact angle is at
least about 125 degrees.
5. The system of claim 1, wherein said hydrophobic coating has a
surface energy .UPSILON..sub.C of less than or equal to about 20.2
mN/m.
6. The system of claim 5, wherein said hydrophobic coating has a
surface energy .UPSILON..sub.C of less than or equal to about 19.5
mN/m.
7. The system of claim 1, wherein said hydrophobic coating has a
surface energy .UPSILON..sub.C of less than or equal to about 18.0
mN/m, and wherein the refractive index "n" of said coating is from
about 1.5 to 1.7.
8. The system of claim 1, wherein said hydrophobic coating is in
direct contact with said glass substrate.
9. The system of claim 1, wherein said hydrophobic coating has an
average hardness of at least about 20 GPa.
10. The system of claim 9, wherein said hydrophobic coating has an
average hardness of from about 20-80 GPa.
11. The system of claim 1, wherein said hydrophobic coating
includes diamond like carbon (DLC) and wherein at least about 50%
of carbon-carbon bonds in said hydrophobic coating are highly
tetrahedral sp.sup.3 carbon-carbon bonds.
12. The system of claim 1, wherein the outermost 10 angstroms (A)
layer portion of said hydrophobic coating includes in atomic
percentage: from about 5-60% carbon (C), from about 0-40% oxygen
(O), from about 0-40% silicon (Si), from about 10-95% hydrogen (H),
and from about 0-10% fluorine (F).
13. The system of claim 1, wherein at least one 10 angstroms (A)
thick layer portion of said hydrophobic coating includes in atomic
percentage: from about 15-80% carbon (C), from about 5-45% oxygen
(O), from about 5-45% silicon (Si), from about 0-30% hydrogen (H),
and from about 0-10% fluorine (F).
14. The system of claim 1, wherein the outermost 5 angstroms (A)
layer portion of said hydrophobic coating includes in atomic
percentage at least about 25%H.
15. The system of claim 1, wherein said air deflector includes an
array of channels defined in a lower surface thereof in order to
increase speed of air flow.
16. The system of claim 15, wherein each of said channels includes
and inlet and an outlet, and wherein an area flow area at said
inlet is greater than an air flow area at said outlet so that air
may exit said channels at a higher rate than when entering the
channels.
17. An air deflector for enabling rain water to be removed from a
major exterior surface of a backlite of a vehicle, said air
deflector comprising: a body for redirecting air from flowing in a
first direction across a surface of a vehicle to a second direction
in which air flows toward a backlite of the vehicle; and wherein
said air deflector includes a plurality of channels defined in a
lower major surface thereof for causing a certain portion of air
which exits said channels to be flowing at a faster rate than when
said portion of air entered said channels, respectively.
18. The air deflector of claim 17, wherein one of said channels is
enclosed on three elongated sides thereof, and open on a fourth
elongated side thereof.
19. A method of blowing water off of a rear window of a vehicle,
said method comprising the steps of: providing a vehicle including
the rear window and an air deflector mounted at an elevation above
at least a portion of the rear window, an exterior surface of the
rear window having a contact angle .theta. of at least about 70
degrees; the air deflector redirecting air flow flowing over an
upper surface of the vehicle and causing the redirected air flow to
flow toward the rear window at an increased rate; and the
redirected air flow flowing across an exterior surface of the rear
window having a contact angle .theta. of at least about 70 degrees
so as to remove water from the surface of the rear window.
20. The method of claim 19, wherein the rear window comprises a
glass substrate having a diamond-like carbon inclusive coating
thereon, and wherein the coating has the contact angle of at least
about 70 degrees.
Description
[0001] This is a continuation-in-part (CIP) of U.S. patent
application Ser. No. 09/303,548, filed May 3, 1999, and Ser. No.
09/442,805, filed Nov. 18, 1999, the disclosures of which are both
hereby incorporated herein by reference in their entireties.
[0002] This invention relates to a system and method for removing
liquid from a rear window (i.e., backlite) of a vehicle such as a
car, truck, or sport utility vehicle. More particularly, the system
and/or method may include a rear spoiler or air deflector designed
to accelerate air/wind flow and direct the same toward the backlite
which may include a hydrophobic coating provided thereon, so that
liquid (e.g., rain) and/or dirt may be easily removed from the
backlite.
BACKGROUND OF THE INVENTION
[0003] Conventionally, rain and dirt are typically removed from
vehicle backlites (i.e., rear windows) using a rear wiper(s),
especially in sport utility vehicles. Unfortunately, rear wipers
tend to be rather fragile, costly and prone to damage.
[0004] In view of the above, it is apparent that there exists a
need in the art for a system and corresponding method for removing
rain and/or dirt from vehicle backlites without the need for use of
a rear wiper.
[0005] Rear spoilers for directing air/wind onto vehicle backlites
are known in the art. For example, see U.S. Pat. Nos. 4,674,788,
4,881,772 and 5,845,960, the disclosures of which are hereby
incorporated herein by reference. The '788 patent discloses a rear
spoiler which may be manipulated between two different positions.
FIG. 1 is a perspective view of vehicle 3 including the '788 rear
spoiler 5 mounted thereon. In the first position, spoiler 5 diverts
air flowing along upper vehicle body surface 7 (i.e., roof)
upwardly so as to exert a downward force and enhance traction of
vehicular wheels 9. In the second position, spoiler 5 guides air
flow toward a rear window (i.e., backlite) 11 surface so as to
remove rain water, dust and so forth from the major exterior
surface thereof.
[0006] Unfortunately, the system of the '788 patent is less than
desirable for at least the following reasons. First, while the
spoiler may guide air flow toward the backlite, it does not serve
to accelerate the speed of the air flow. Thus, when the vehicle is
traveling at rather slow speeds (e.g., 20 mph), the air flow will
often be insufficient to clean/remove rain and the like from the
surface of backlite 11. Second, the backlite appears to be of
conventional glass in the '788 patent (the contact angle .theta. of
conventional uncoated soda lime silica glass is about 22-24
degrees). As a result, even when air is caused to flow across the
surface of the backlite, rain may not be sufficiently removed
therefrom due to the inherent tendency of glass to hold water on
its surface due to its naturally low contact angle .theta..
[0007] The '772 and '960 patents also disclose rear spoilers
designed to direct air flow toward backlites. Unfortunately, the
'772 and '960 patents suffer from the same problem as the '788
patent in that the backlite appears to be of conventional glass
thus having an inherently low contact angle .theta.. As a result,
even when air is caused to flow across the surface of the backlite,
rain may not be sufficiently removed therefrom due to the natural
tendency of glass to hold water on its surface due to its
inherently low contact angle .theta..
[0008] It will be apparent from the above that there exists a need
in the art for a system and/or method for efficiently removing
water (e.g., rain) from the exterior surface of a rear
backlite.
[0009] It is a purpose of different embodiments of this invention
to fulfill any or all of the above described needs in the art,
and/or other needs which will become apparent to the skilled
artisan once given the following disclosure.
SUMMARY OF THE INVENTION
[0010] An object of this invention is to provide a system and/or
method for efficiently removing liquid such as rain from an
exterior surface of a vehicle backlite (i.e., rear window).
[0011] Another object of this invention is to reduce the need for a
rear wiper on a vehicle by providing a system and/or method which
may remove a significant amount of liquid such as rain from the
backlite without the need for a wiper.
[0012] Another object of this invention is to provide a rear
spoiler including a plurality of venturi-like channels or passages
therein for accelerating air flow and directing the accelerated air
flow toward a surface of the backlite.
[0013] Another object of this invention is to provide a hydrophobic
coating on the exterior major surface of a vehicle backlite so as
to enable air flowing over the surface to more easily remove (or
blow off) liquid such as rain therefrom.
[0014] Yet another object of this invention is to provide a
hydrophobic coating on a vehicle backlite to be used in combination
with a spoiler designed to accelerate air flow and/or direct the
same toward the backlite with hydrophobic coating thereon, in order
to efficiently remove liquid such as rain from the coated surface
of the backlite. This may eliminate the need for a rear wiper in
certain embodiments, and in other embodiments where a rear wiper is
provided on the vehicle may reduce the need for its use to remove
rain and/or dirt from the backlite's exterior major surface.
[0015] Another object of this invention is to provide the backlite
with a hydrophobic coating including sp.sup.3 carbon-carbon bonds
and a wettability W with regard to water of less than or equal to
about 23 mN/m, more preferably less than or equal to about 21 mN/m,
and most preferably less than or equal to about 20 mN/m, and in
most preferred embodiments less than or equal to about 19 mN/meter
(these units may also be explained or measured in Joules per unit
area (MJ/m.sup.2)).
[0016] Another object of this invention is to provide the backlite
with a hydrophobic coating including sp.sup.3 carbon-carbon bonds
and a surface energy .UPSILON..sub.C of less than or equal to about
20.2 mN/m, more preferably less than or equal to about 19.5 mN/m,
and most preferably less than or equal to about 18 mN/m.
[0017] Another object of this invention is to provide the backlite
with a hydrophobic coating thereon, the backlite with coating
having an initial (i.e. prior to being exposed to environmental
tests, rubbing tests, acid tests, UV tests, or the like) water
contact angle .theta. of at least about 70 degrees, more preferably
of at least about 100 degrees, even more preferably of at least
about 110 degrees, and most preferably of at least about 125
degrees.
[0018] Another object of this invention is to provide a hydrophobic
coating for a vehicle backlite, wherein at least about 15% (more
preferably at least about 25%, and most preferably at least about
30%) of the bonds in the coating are sp.sup.3 carbon-carbon (C--C)
bonds; and wherein the coating includes by atomic percentage at
least about 5% silicon (Si) atoms (more preferably at least about
15%, and most preferably at least about 20% Si), at least about 5%
oxygen (O) atoms (more preferably at least about 15% and most
preferably at least about 20%), at least about 5% hydrogen (H)
atoms (more preferably at least about 10% and most preferably at
least about 15%) taking into consideration either the coating's
entire thickness or only a thin layer portion thereof. In certain
embodiments, an increased percentage of H atoms may be provided
near the coating's outermost surface. In certain embodiments, the
coating has approximately the same amounts of C and Si atoms.
[0019] Another object of this invention is to provide a coating for
a vehicle backlite, wherein the coating includes a greater number
of sp.sup.3 carbon-carbon (C--C) bonds than SP.sup.2 carbon-carbon
(C--C) bonds. In certain of these embodiments, the coating need not
include any sp.sup.2 carbon-carbon (C--C) bonds.
[0020] Another object of this invention is to provide a
diamond-like carbon (DLC) coating on the major exterior surface of
a vehicle backlite, wherein the coating includes different portions
or layers with different densities and different sp.sup.3
carbon-carbon bond percentages. The ratio of sp.sup.3 to sp.sup.2
carbon-carbon bonds may be different in different layers or
portions of the coating. Such a coating with varying compositions
therein may be continuously formed by varying the ion energy used
in the deposition process so that stresses in the coating are
reduced in the interfacial portion/layer of the DLC coating
immediately adjacent the underlying substrate. Thus, a DLC coating
may have therein an interfacial layer with a given density and
sp.sup.3 carbon-carbon bond percentage, and another layer portion
proximate a mid-section of the coating having a higher density of
sp.sup.3 carbon-carbon (C--C) bonds. The outermost layer portion at
the surface of the coating may be doped (e.g. addition of Si, O
and/or F) so that this surface portion of the coating is less dense
which increases contact angle and decreases the dispersive
component of surface energy so as to improve hydrophobic
characteristics of the coating.
[0021] Still another object of this invention is to fulfill any or
all of the above-listed objects and/or needs.
[0022] Generally speaking, this invention fulfills any or all of
the above described needs or objects by providing a method of
blowing water off of a rear window of a vehicle, the method
comprising the steps of:
[0023] providing a vehicle including the rear window and an air
deflector mounted at an elevation above at least a portion of the
rear window, an exterior surface of the rear window having a
contact angle .theta. of at least about 70 degrees;
[0024] the air deflector redirecting air flow flowing over an upper
surface of the vehicle and causing the redirected air flow to flow
toward the rear window at an increased rate; and
[0025] the redirected air flow flowing across an exterior surface
of the rear window having a contact angle of at least about 70
degrees so as to remove water from the surface of the rear
window.
[0026] This invention further fulfills any of all of the above
listed needs and/or objects by providing a system for enabling rain
water to be removed from a major exterior surface of a backlite
(i.e., rear window) of a vehicle, the system comprising:
[0027] an air deflector for redirecting air from flowing in a first
direction across a surface of the vehicle to a second direction in
which air flows downwardly toward the backlite, and for causing at
least a portion of the air flowing the second direction to flow
faster than air in the first direction; and
[0028] wherein said backlite includes a substrate with a
hydrophobic coating thereon, so that the major exterior surface of
the backlite has an initial contact angle .theta. of at least about
70 degrees.
[0029] This invention will now be described with respect to certain
embodiments thereof, along with reference to the accompanying
illustrations.
IN THE DRAWINGS
[0030] FIG. 1 is a perspective view of a vehicle with a
conventional rear spoiler mounted thereon.
[0031] FIG. 2 is a side view of a portion of a vehicle according to
an embodiment of this invention, including respective portions of
the vehicle backlite and roof illustrated cross sectionally and the
rear air deflector or spoiler illustrated in an elevational manner
(not cross sectionally).
[0032] FIG. 3 is an elevation or plan view of a portion of the rear
air deflector of FIG. 2 according to one embodiment of this
invention, taken from a viewpoint "A" located between the deflector
and roof in FIG. 2.
[0033] FIG. 4 is an elevation or plan view of a portion of the rear
air deflector of FIG. 2 according to another embodiment of this
invention, taken from a viewpoint "A" located between the deflector
and roof in FIG. 2.
[0034] FIG. 5 is a side cross sectional view of a coated vehicle
backlite according to an embodiment of this invention, wherein a
glass or plastic substrate is provided with a DLC inclusive coating
thereon having hydrophobic qualities.
[0035] FIG. 6 is a side cross sectional view of a coated vehicle
backlite according to another embodiment of this invention, wherein
first and second DLC inclusive coatings are provided on a substrate
of glass or plastic.
[0036] FIG. 7 is a side cross-sectional view of a coated vehicle
backlite according to yet another embodiment of this invention
wherein a low-E or other coating is provided on a substrate, with
the hydrophobic DLC inclusive coating(s) of either of the FIG. 5 or
FIG. 6 embodiments also on the substrate but over top of the
intermediate low-E or other coating.
[0037] FIG. 8 is a side cross sectional partially schematic view
illustrating a low contact angle .theta. of a drop on an uncoated
glass substrate.
[0038] FIG. 9 is a side cross sectional partially schematic view
illustrating the coated backlite of any embodiment herein and the
contact angle .theta. of a water drop thereon.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THIS INVENTION
[0039] Referring now more particularly to the accompanying drawings
in which like reference numerals indicate like elements throughout
the accompanying views.
[0040] FIG. 2 illustrates vehicle upper surface or roof section 7
in cross section, vehicle rear window or backlite 13 in cross
section, and rear spoiler or air deflector 15 in an elevational
manner. FIGS. 3-4 are elevational or plan view of a portion of
deflector 15 as viewed from approximately point "A" in FIG. 2,
according to different embodiments of this invention.
[0041] Referring to FIGS. 2-4, when the vehicle (e.g., see vehicle
3 in FIG. 1 or any other type of vehicle such as a sport utility
vehicle, sports car, mini-van, sedan, or the like) is being driven
in the forward direction 16, deflector 15 functions to (i) redirect
air 17 flowing across the roof 7 of the vehicle downwardly in a
direction 18 toward the exterior major surface 19 of backlite 13,
(ii) accelerate the speed of air flow as the air is directed toward
surface 19 of backlite 13, and/or (iii) support one or more spray
nozzles 21 for spraying or otherwise directing cleaning fluid
(e.g., water or cleanser) 23 onto surface 19 of backlite 13 so that
dirt and the like may be more easily removed therefrom (i.e., blown
off) by airflow 18 passing over the surface of backlite 13.
[0042] In certain embodiments, a portion of rear air deflector 15
may define a plane 25 which is angled .phi. from about 25-60
degrees, more preferably from about 40-50 degrees, relative to the
horizontal 27. This causes the air deflecting surfaces of deflector
15 to be aligned in similar angle(s) relative to the horizontal so
that air 17 can be redirected 18 toward surface 19 of backlite 13
to be cleaned. Deflector alignment angle .phi. is chosen for each
application as a function of the inclination of the backlite and/or
roof of the vehicle.
[0043] Conventional glass tends to hold water thereon (i.e., has a
low contact angle). Thus, it is difficult to remove water (e.g.,
rain) from the surface of conventional backlite simply by causing
air to be blown over the surface of the backlite. This is
especially true when the vehicle is moving at relatively slow
speeds of from about 0-35 miles per hour (mph). In order to solve
this problem, applicants have provided a hydrophobic coating (see
FIGS. 5-7 and 9) on the major exterior surface 19 of backlite 13
and have also designed deflector 15 so that it may increase the
speed of airflow as air is directed toward the hydrophobically
coated backlite. This combination (i.e., hydrophobic coating on the
backlite with an air flow accelerating deflector) enables water and
the like to be easily removed from surface 19 of backlite 13 by
airflow 18 when the vehicle is moving even at lower speeds of from
about 20-35 mph.
[0044] Two aspects of deflector 15 cause acceleration of air flow
(i.e., air flow 18 flows at a higher speed or rate than air flow
17). Each involves the area of air input to the area of deflector
15 area being greater than the area of air output from the area of
deflector 15 (while the volume of air at each is approximately
equal). First, distance d1 (the distance between an air input end
of deflector 15 and the vehicle surface) is greater than distance
d2 (the distance between an air output end of deflector 15 and the
vehicle surface). Because d1>d2, the mass of the air flowing by
the deflector is compacted by the deflector into a significantly
smaller area so that the rate of flow increases as it is directed
toward backlite 13. Second, the array of air flow channels 31
defined in the bottom surface 32 of the deflector, as best shown in
the embodiments of FIGS. 3-4, also creates a venturi-like effect so
as to increase the air flow speed as the air is directed toward
surface 19 of the backlite.
[0045] When the vehicle is moving in forward direction 16, air 17
flows across the roof of the vehicle. A portion 33 of that air is
driven into channels 31 defined in deflector 15. Because the
channels are tapered or narrowed via channel sidewalls 34 from
their input ends 35 to their respective output ends 37, the
pressure of the air within the channels 31 increases so as to reach
a maximum pressure in each channel at respective channel outputs
37. The compressed air exiting channels 31 is thus caused to flow
at a higher speed (i.e., accelerate). The air leaving channels
expands and flows toward the backlite at 18. The tapering of air
flow area due to d1>d2 creates a similar effect. The result is
that the air flow speed at 18 as the air flow across surface 19 of
backlite 13 is higher than the air flow speed at 17 before the air
crosses deflector 15.
[0046] In certain embodiments of this invention, as shown in FIGS.
2-4, channels 31 are defined in the lower surface 32 of air
deflector 15. In other words, channels 31 may be said to be cut out
of the main body of the deflector, so that each channel 31 is
defined by sidewalls 34 on opposing sides thereof and by a wall 36
of the main deflector body on another side thereof. Therefore, each
channel 31 is enclosed on three elongated sides thereof, and open
on a fourth elongated side along the length of the channel closest
to the vehicle. By designing channels 31 so as to be open along the
entire side(s) thereof facing the vehicle, a portion of the air
flowing past the defector 15 is caused to flow through channels 31
while another portion is caused to flow closer to the vehicle and
not within the confines of any of the channels. Because channels 31
cause air output therefrom at outlets 37 to flow in high rate
jet-like streams (which do not cover the entire backlite surface
19), the channels being open at one major side thereof may enable
the air flow across surface 19 to cover more of the surface area of
the backlite and therefor do a better job of cleaning than if the
channels were entirely enclosed along their respective lengths.
[0047] While channels 31 are open along one elongated side thereof
in the illustrated embodiments, it is recognized that in other
embodiments of this invention, channels 31 may be entirely enclosed
along their respective lengths, with the only openings being those
of the respective air inlets and air outlets. Moreover, while
channels 31 are illustrated in FIGS. 3-4 as being approximately
triangular in shape, such channels may be of any other suitable
shape in other embodiments of this invention so long as air flow
rate is increased thereby.
[0048] In certain embodiments of this invention, a plurality of
window washing spray jets 21 may be provided on, e.g., an
underneath side/surface of deflector 15, as shown in FIGS. 2 and 3.
This enables the cleaning fluid output by jets 21 to be more
efficiently inserted into the air flow streams 18 being directed
toward the backlite in the direction of air flow.
[0049] In order to enable air flow 18 to efficiently remove liquid
(e.g., rain water) and the like from surface 19 of backlite 13, the
backlite includes a hydrophobic coating as illustrated in any of
FIGS. 5-7 and 9.
[0050] FIG. 5 is a side cross-sectional view of a coated backlite
13 according to an embodiment of this invention, wherein at least
one diamond-like carbon (DLC) inclusive protective coating(s) 43 is
provided directly on substrate 41. Substrate 41 may be of glass,
plastic, or the like. DLC inclusive coating 43 in the FIG. 5
embodiment includes at least one layer including highly tetrahedral
amorphous carbon (ta-C). Coating 43 functions in a hydrophobic
manner (i.e. it is characterized by high water contact angles
.theta. and/or low surface energies as described below). In certain
embodiments, coating 43 may be from about 50-1,000 angstroms (A)
thick, more preferably from about 100-500 angstroms (A) thick, and
most preferably from about 150-200 angstroms (A) thick.
[0051] In certain embodiments, hydrophobic coating 43 may have an
approximately uniform distribution of sp.sup.3 carbon-carbon bonds
throughout a large portion of its thickness, so that much of the
coating has approximately the same density. In other more preferred
embodiments, hydrophobic coating 43 may include a lesser percentage
of sp.sup.3 carbon-carbon bonds near the interface with substrate
41, with the percentage or ratio of sp.sup.3 carbon-carbon bonds
increasing throughout the thickness of the coating toward the
outermost surface. Thus, coating 43 may include at least one
interfacing layer directly adjacent substrate 41, this interfacing
layer having a lesser density and a lesser percentage of sp.sup.3
carbon-carbon bonds than the middle portion of DLC inclusive
coating 43. In general, the network of sp.sup.3 carbon-carbon bonds
functions to hold the other atoms (e.g. Si, O, F, and/or H atoms)
around it in the coating. In certain embodiments, it is desired to
keep number of SP.sup.2 carbon-carbon bonds throughout the entire
thickness of the coating to no greater than about 25%, more
preferably no greater than about 10%, and most preferably from
about 0-5%, as these type bonds are hydrophillic in nature and
attract water and the like. Thus, in preferred embodiments, at
least about 50% (more preferably at least about 75%, and most
preferably at least about 90%) or the carbon-carbon bonds in
coating 43 are of the sp.sup.3 carbon-carbon type.
[0052] The presence of sp.sup.3 carbon-carbon bonds in coating 43
increases the density and hardness of the coating, thereby enabling
it to satisfactorily function in automotive environments. In
certain embodiments, taking only a thin layer portion of, or
alternatively the entire thickness of, coating 43 into
consideration, at least about 15% (more preferably at least about
25%, and most preferably at least about 30%) of the bonds in the
coating or coating layer portion are sp.sup.3 carbon-carbon (C--C)
bonds (as opposed to sp.sup.2 carbon-carbon bonds). Coating 43 may
or may not include sp.sup.2 carbon-carbon bonds in different
embodiments (if so, most sp.sup.2 carbon-carbon bonds may be
provided at the portion of the coating interfacing with the
underlying substrate).
[0053] In order to improve the hydrophobic nature of coating 43,
atoms other than carbon (C) are provided in the coating in
different amounts in different embodiments. For example, in certain
embodiments of this invention coating 43 (taking the entire coating
thickness, or only a thin 10 angstroms (A) thick layer portion
thereof into consideration) may include in addition to the carbon
atoms of the sp.sup.3 carbon-carbon bonds, by atomic percentage, at
least about 5% silicon (Si) atoms (more preferably at least about
15%, and most preferably at least about 20% Si), at least about 5%
oxygen (O) atoms (more preferably at least about 15% and most
preferably at least about 20% O), at least about 5% hydrogen (H)
atoms (more preferably at least about 10% and most preferably at
least about 15% H). In certain preferred embodiments, the atomic
percentage of C and Si atoms in coating 43 are approximately equal.
Optionally, coating 43 may include and from about 0-10% (atomic
percentage) fluorine (F) (more preferably from about 0-5% F) in
order to further enhance hydrophobic characteristics of the
coating.
[0054] In certain embodiments, the outermost thin layer portion of
hydrophobic coating 43 may also include a larger percentage of H
atoms deposited via plasma ion beam treatment relative to the rest
of the coating in order to reduce the number of polar bonds at the
coating's surface, thereby improving the coating's hydrophobic
properties by reducing the polar component of the surface energy.
For example, in certain embodiments the outermost 5 angstroms (A)
layer portion of coating 43 may include at least about 10% H atoms,
more preferably at least about 25% H atoms, and most preferably at
least about 50% H atoms. This higher concentration or percentage of
H atoms near the surface of coating 43 is illustrated in FIGS. 5-7
by the dots which become more concentrated near the coating's
surface 19. The deposition of these H atoms near the coating's
surface 19 results in a more passive or non-polar coating surface.
It is noted that deposition of the H atoms near the coating's
surface 19 may tend to etch away any sp.sup.2 or graphite C--C
bonds in that area. This increase in H near the coating's surface
also decreases the coating's density at this outermost 5 angstroms
(A) layer portion.
[0055] Accordingly, in certain preferred embodiments of this
invention, coating 43 as a whole or any 10 angstroms (A) thick
layer portion thereof (e.g. a 10 angstroms (A) thick portion near
the middle of the coating) may include in atomic percentage: from
about 15-80% carbon (C) (mostly via sp.sup.3 bonds), from about
5-45% oxygen (O), from about 5-45% silicon (Si), from about 0-30%
hydrogen (H), and from about 0-10% fluorine (F). The outermost 5
angstroms (A) layer portion of coating 43 may include in atomic
percentage: from about 5-60% carbon (C) (mostly via sp.sup.3
bonds), from about 0-40% oxygen (O), from about 0-40% silicon (Si),
from about 10-60% hydrogen (H), and from about 0-10% fluorine (F).
As discussed above, additional H may be provided at the outermost
portion of layer 43, largely at the expense of C, in order to
reduce surface energy. An example of a 10 A thick layer portion
near the middle of coating 43 is as follows, by atomic percentage:
35% C, 30% Si, 15% H, and 20% O. An example of the outermost 5 A
thick layer portion of coating 43 is as follows, by atomic
percentage: 20% C, 15% Si, 50% H, and 15% O. Optionally, in certain
preferred embodiments, from about 0-5% F may also be provided in
this outermost 5 A thick layer portion. It is noted that many of
the Si, H, O, and F atoms in the coating are connected to many
carbon atoms via sp.sup.3 bonds. A substantial number of Si--O,
C--C sp.sup.3, Si--C sp.sup.3, and C--H sp.sup.3 bonds are thus
present. In certain embodiments, the Si--O bonds tend to cancel out
some of the charge due to the carbon thereby reducing surface
energy. The presence of the O also reduces density and permits the
dispersive component of surface energy to be reduced. These
examples are for purposes of example only, and are not intended to
be limiting in any way,
[0056] In certain preferred embodiments, coating 43 has an average
hardness of at least about 10 GPa, more preferably at least about
20 GPa, and most preferably from about 20-50 GPa. Such hardness
renders coating 43 resistant to scratching, solvents, and the like.
It is noted that the hardness and density of coating 43 and/or
layer 47 may be adjusted by varying the ion energy of the
depositing apparatus or process described below.
[0057] FIG. 6 is a side cross sectional view of a coated backlite
13 according to another embodiment of this invention, including
substrate 41 (e.g. glass), hydrophobic DLC inclusive coating 43 as
described above with regard to the FIG. 5 embodiment, and
intermediate DLC inclusive layer 47 sandwiched therebetween. In
certain embodiments, at least about 35% of the bonds in layer 47
may be of the sp.sup.3 C--C type, more preferably at least about
70%, and most preferably at least about 80%. Any of the DLC
inclusive layers described in Ser. No. 09/303,548 (incorporated
herein by reference) may be used as layer 47. In effect, layer 47
may function in certain embodiments to reduce corrosion of the
coated backlite (e.g. when the substrate includes Na, or is
soda-lime-silica glass), while overlying coating 43 provides a
hydrophobic function.
[0058] In the FIG. 7 embodiment, a low-E or other coating 49 is
provided between substrate 41 and hydrophobic DLC inclusive coating
43. However, coating 43 is still on substrate 41 in the FIG. 7
embodiment. The term "on" herein means that substrate 41 supports
DLC coating 43 or any layer portion thereof, regardless of whether
or not other layer(s) (e.g. 47, 49) are provided therebetween.
Thus, protective coating 43 may be provided directly on substrate
41 as shown in FIG. 5, or may be provided on substrate 41 with a
low-E or other coating(s) 47 therebetween as shown in FIGS. 6-7. In
still other embodiments, a low-E coating(s) 49 may be provided
between hydrophobic coating 43 and DLC layer 47 of the FIG. 6
embodiment).
[0059] Exemplar coatings (in full or any portion of these coatings)
that may be used as low-E or other coating(s) 49 are shown and/or
described in any of U.S. Pat. Nos. 5,837,108, 5,800,933, 5,770,321,
5,557,462, 5,514,476, 5,425,861, 5,344,718, 5,376,455, 5,298,048,
5,242,560, 5,229,194, 5,188,887 and 4,960,645, which are all hereby
incorporated herein by reference. Silicon oxide and/or silicon
nitride coating(s) may also be used as coating(s) 49.
[0060] As will be discussed in more detail below, highly
tetrahedral amorphous carbon (ta-C) forms sp.sup.3 carbon-carbon
bonds, and is a special form of diamond-like carbon (DLC). The
amounts of sp.sup.3 bonds may be measured using Raman
finger-printing and/or electron energy loss spectroscopy. A high
amount of sp.sup.3 bonds increases the density of a layer, thereby
making it stronger and allowing it to reduce soda diffusion to the
surface of the coated article. However, in certain embodiments,
there is a lesser percentage of such bonds at the outmost layer
portion of coating 43 than at middle areas of the coating, so that
H atoms may be provided in order to improve the coating's
hydrophobic characteristics.
[0061] In certain embodiments, hydrophobic coating 43 is at least
about 75% transparent to or transmissive of visible light rays,
preferably at least about 85%, and most preferably at least about
95%.
[0062] When substrate 41 is of glass, it may be from about 1.5 to
5.0 mm thick, preferably from about 2.3 to 4.8 mm thick, and most
preferably from about 3.7 to 4.8 mm thick. Thus, ta-C inclusive
coating 43 and/or layer 47 reduce the amount of soda that can reach
the surface of the coated article and cause stains/corrosion. In
certain embodiments, substrate 41 includes, on a weight basis, from
about 60-80% SiO.sub.2, from about 10-20% Na.sub.2O, from about
0-16% CaO, from about 0-10% K.sub.2O, from about 0-10% MgO, and
from about 0-5% Al.sub.2O.sub.3. In certain other embodiments,
substrate 41 may be soda lime silica glass including, on a weight
basis, from about 66-75% SiO.sub.2, from about 10-20% Na.sub.2O,
from about 5-15% CaO, from about 0-5% MgO, from about 0-5%
Al.sub.2O.sub.3, and from about 0-5% K.sub.2O. Most preferably,
substrate 41 is soda lime silica glass including, by weight, from
about 70-74% SiO.sub.2, from about 12-16% Na.sub.2O, from about
7-12% CaO, from about 3.5 to 4.5% MgO, from about 0 to 2.0%
Al.sub.2O.sub.3, from about 0-5% K.sub.2O, and from about 0.08 to
0.15% iron oxide. In certain embodiments, any glass disclosed in
U.S. Pat. No. 5,214,008 or Pat. No. 5,877,103, each incorporated
herein by reference, may be used as substrate 41. Also, soda lime
silica float glass available from Guardian Industries Corp., Auburn
Hills, Mich., may be used as substrate 41.
[0063] Any such aforesaid glass substrate 41 may be, for example,
green, blue or grey in color when appropriate colorant(s) are
provided in the glass in certain embodiments.
[0064] In certain other embodiments of this invention, substrate 41
may be of borosilicate glass, or of substantially transparent
plastic. In certain borosilicate embodiments, the substrate 41 may
include from about 75-85% SiO.sub.2, from about 0-5% Na.sub.2O,
from about 0 to 4% Al.sub.2O.sub.3, from about 0-5% K.sub.2O, from
about 8-15% B.sub.2O.sub.3, and from about 0-5% Li.sub.2O.
[0065] When substrate 41 is coated with at least DLC coating 43
according to any of the FIGS. 5-7 embodiments, the resulting coated
backlite 13 may have the following characteristics in certain
embodiments: visible transmittance (Ill. A) greater than about 60%
(preferably greater than about 70%, and most preferably greater
than about 80%), UV (ultraviolet) transmittance less than about
38%, total solar transmittance less than about 45%, and IR
(infrared) transmittance less than about 35% (preferably less than
about 25%, and most preferably less than about 21%). Visible,
"total solar", UV, and IR transmittance measuring techniques are
set forth in Pat. No. 5,800,933, as well as the '008 patent,
incorporated herein by reference.
[0066] Hydrophobic performance of coating 43 in any of the above
embodiments is a function of contact angle .theta., surface energy
.UPSILON., and wettability or adhesion energy W. The surface energy
.UPSILON. of coating 43 may be calculated by measuring its contact
angle .theta. (contact angle .theta. is illustrated in FIGS. 8-9).
A sessile drop 51 of a liquid such as water is placed on the
coating as shown in FIG. 9. A contact angle .theta. between the
drop 51 and underlying coating 43 appears, defining an angle
depending upon the interface tension between the three phases in
the point of contact. Generally, the surface energy .UPSILON..sub.C
of coating 43 can be determined by the addition of a polar and a
dispersive component, as follows:
.UPSILON..sub.C=.UPSILON..sub.CP+.UPSILON..sub.CD, where
.UPSILON..sub.CP is the coating's polar component and
.UPSILON..sub.CD the coating's dispersive component. The polar
component of the surface energy represents the interactions of the
surface which is mainly based on dipoles, while the dispersive
component represents, for example, van der Waals forces, based upon
electronic interactions. Generally speaking, the lower the surface
energy .UPSILON..sub.C of coating 43, the more hydrophobic the
coating and the higher the contact angle .theta..
[0067] Adhesion energy (or wettability) W can be understood as an
interaction between polar with polar, and dispersive with
dispersive forces, between coating 43 and a liquid thereon such as
water. .UPSILON..sup.P is the product of the polar aspects of
liquid tension and coating/substrate tension; while .UPSILON..sup.D
is the product of the dispersive forces of liquid tension and
coating/substrate tension. In other words,
.UPSILON..sup.P=.UPSILON..sub.LP*.UPSILON..sub.CP; and
.UPSILON..sup.D=.UPSILON..sub.LD*.UPSILON..sub.CD; where
.UPSILON..sub.LP is the polar aspect of the liquid (e.g. water),
.UPSILON..sub.CP is the polar aspect of coating 43;
.UPSILON..sub.LD is the dispersive aspect of liquid (e.g. water),
and .UPSILON..sub.CD is the dispersive aspect of coating 43. It is
noted that adhesion energy (or effective interactive energy) W,
using the extended Fowkes equation, may be determined by:
W=[.UPSILON..sub.LP*.UPSILON..sub.CP].sup.1/2+[.UPSILON..sub.LD*.UPSILON..-
sub.CD].sup.1/2=.UPSILON..sub.1(1+cos .theta.),
[0068] where .UPSILON..sub.1 is liquid tension and .theta. is the
contact angle. W of two materials (e.g. coating 43 and water
thereon) is a measure of wettability indicative of how hydrophobic
the coating is.
[0069] When analyzing the degree of hydrophobicity of coating 43
with regard to water, it is noted that for water .UPSILON..sub.LP
is 51 mN/m and .UPSILON..sub.LD is 22 mN/m. In certain embodiments
of this invention, the polar aspect .UPSILON..sub.CP of surface
energy of coating 43 is from about 0 to 0.2 (more preferably
variable or tunable between 0 and 0.1) and the dispersive aspect
.UPSILON..sub.CD of the surface energy of coating 43 is from about
16-22mN/m (more preferably from about 16-20 mN/m).
[0070] Using the above-listed numbers, according to certain
embodiments of this invention, the surface energy .UPSILON..sub.C
of coating 43 is less than or equal to about 20.2 mN/m, more
preferably less than or equal to about 19.5 mN/m, and most
preferably less than or equal to about 18.0 mN/m; and the adhesion
energy W between water and coating 43 is less than about 25 mN/m,
more preferably less than about 23 mN/m, even more preferably less
than about 20 mN/m, and most preferably less than about 19 mN/m.
These low values of adhesion energy W and coating 43 surface energy
.UPSILON..sub.C, and the high initial contact angles .theta.
achievable, illustrate the improved hydrophobic nature of coatings
43 according to different embodiments of this invention.
[0071] The initial contact angle .theta. of a conventional glass
substrate 41 with sessile water drop 51 thereon is typically from
about 22-24 degrees, as llustrated in FIG. 8. Thus, conventional
glass substrates are not particularly hydrophobic in nature. The
provision of coating(s) 43 on substrate 41 causes the contact angle
.theta. to increase to the angles discussed above, as shown in FIG.
9 for example, thereby improving the hydrophobic nature of the
backlite 13. As discussed in Table 1 of Ser. No. 09/303,548, the
contact angle .theta. of a ta-C DLC layer is typically from about 5
to 50 degrees. However, the makeup of DLC-inclusive coating 43
described herein enables the initial contact angle .theta. between
coating 43 and a water drop (i.e. sessile drop 51 of water) to be
increased in certain embodiments to at least about 100 degrees,
more preferably at least about 110 degrees, even more preferably at
least about 115 degrees, and most preferably at least about 125
degrees, thereby improving the hydrophobic characteristics of the
DLC-inclusive material and enabling air flow 18 to more easily
remove rain and the like from the surface of backlite 13. An
"initial" contact angle .theta. means prior to exposure to
environmental conditions such as sun, rain, humidity, etc.
[0072] Prior to coating 43 being formed on glass substrate 41, the
top surface of substrate 41 is preferably cleaned by way of a first
linear or direct ion beam source. For example, a glow discharge in
argon (Ar) gas or mixtures of Ar/O.sub.2 (alternatively CF.sub.4
plasma) may be used to remove any impurities on the substrate
surface. Such interactions are physio-chemical in nature. This
cleaning creates free radicals on the substrate surface that
subsequently can be reacted with other monomers yielding substrate
surfaces with specialized properties. The power used may be from
about 100-300 Watts. Substrate 41 may also be cleaned by, for
example, sputter cleaning the substrate prior to actual deposition
of coating 43; using oxygen and/or carbon atoms at an ion energy of
from about 800 to 1200 eV, most preferably about 1,000 eV.
[0073] After cleaning, the deposition process begins using a linear
ion beam deposition technique via a second ion beam source; with a
conveyor having moved the cleaned substrate 41 from the first
source to a position under the second source. The second ion beam
source functions to deposit a ta-C/SiO (or ta-C/SiO:F in
alternative embodiments) coating 43 onto substrate 41, as follows.
In preferred embodiments, the ratio of C to Si in coating 43 is
approximately 1:1 (i.e. 1:1 plus/minus about 20%). However, in
other preferred embodiments (e.g. see XPS analyzed Sample Nos. 1-3
below), the ratio of C to Si in coating 43 may be from about 1:1 to
4:1. The dopant gas may be produced by bubbling a carrier gas (e.g.
C.sub.2H.sub.2) through the precursor monomer (e.g. TMS or 3MS)
held at about 70 degrees C (well below the flashing point).
Acetylene feedstock gas (C.sub.2H.sub.2) is used in certain
embodiments to prevent or minimize/reduce polymerization and to
obtain an appropriate energy to allow the ions to penetrate the
substrate 41 or other surface and subimplant therein, thereby
causing coating 43 atoms to intermix with the surface of substrate
41 (or the surface of the growing coating) a few atom layers
thereinto. In alternative embodiments, the dopant gas may be
produced by heating or warming the monomer (e.g. to about 25-30
degrees C) so that vapor therefrom proceeds through a mass flow
controller to the ion beam source; so that C.sub.2H.sub.2 is not
needed. The actual gas flow may be controlled by a mass flow
controller (MFC) which may be heated to about 70 degrees C. Oxygen
(O.sub.2) gas is independently flowed through an MFC. In certain
embodiments, a target consisting essentially of approximately equal
molar percentages of C and Si may be isostatically compressed at
about 20 MPa. The temperature of substrate 41 may be room
temperature; an arc power of about 1000 W may be used; precursor
gas flow may be about 25 sccm; the base pressure may be about
10.sup.-6 Torr, and a Hoescht type carbon electrode may be used.
Coating 43 is preferably free of pinholes to achieve satisfactory
water repulsion and/or suppression of soda diffusion.
[0074] The C--C sp.sup.3 bonding in coating 43 is preferably formed
by having a predetermined range of ion energy prior to reaching
substrate 41, or prior to reaching a coating or layer growing on
the substrate. The optimal ion energy window for the majority of
coating 43 is from about 100-200 eV (preferably from about 100-150
eV) per carbon ion. At these energies, the carbon in coating 43
(and layer 47) emulates diamond, and sp.sup.31 C--C bonds form in
coating 43. However, compressive stresses can develop in ta-C when
being deposited at 100-150 eV. Such stress can reach as high as 10
GPa and can potentially cause delamination from many substrates. It
has been found that these stresses can be controlled and decreased
by increasing the ion energy during the deposition process to a
range of from about 200-1,000 eV. The plasma ion beam source
enables ion energy to be controlled within different ranges in an
industrial process for large area deposition utilized herein. The
compressive stress in amorphous carbon is thus decreased
significantly at this higher ion energy range of 200-1,000 eV.
[0075] High stress is undesirable in the thin interfacing portion
of coating 43 that directly contacts the surface of a glass
substrate 41 in the FIG. 5 embodiment (and the thin interfacing
layer portion of layer 47 in the FIG. 6 embodiment). Thus, for
example, the first 1-40% thickness (preferably the first 1-20% and
most preferably the first 5-10% thickness) of coating 43 (or layer
47) is deposited on substrate 41 using high anti-stress energy
levels of from about 200-1,000 eV, preferably from about 400-500
eV. Then, after this initial interfacing layer portion of coating
43 has been grown, the ion energy in the ion deposition process is
decreased (either quickly or gradually while deposition continues)
to about 100-200 eV, preferably from about 100-150 eV, to grow the
remainder of coating 43 (or layer 47). Thus, in certain
embodiments, because of the adjustment in ion energy during the
deposition process, DLC inclusive coating 43 in FIGS. 5-7 has
different densities and different percentages of sp.sup.3 C--C
bonds at different layer portions thereof (the lower the ion
energy, the more sp.sup.3 C--C bonds and the higher the
density).
[0076] While direct ion beam deposition techniques are preferred in
certain embodiments, other methods of deposition may also be used
in different embodiments. For example, filtered cathodic vacuum arc
ion beam techniques may be used to deposit coating 43 and/or layer
47. Also, in certain embodiments, CH.sub.4 may be used as a
feedstock gas during the deposition process instead of or in
combination with the aforesaid C.sub.2H.sub.2 gas. Alternatively,
any of the deposition methods disclosed in U.S. Pat. No. 5,858,477
may be used to deposit coating 43 and/or layer 47, the disclosure
of Pat. No. 5,858,477 hereby being incorporated herein by
reference.
[0077] In certain alternative embodiments of this invention, the
second source may deposit a ta-C:SiO:F coating 43 on substrate 41
instead of a ta-C:SiO coating. The n, k and Tauc optical bandgap
may be tailored by doping the bulk of coating 43 with F and/or H;
where "n" is refractive index and "k" is extinction coefficient. As
the refractive index n of glass is approximately 1.5, it is
desirable in certain embodiments for the refractive index n of
coating 43 to be close to that of the underlying glass substrate 41
in order to achieve good transmission and minimal reflection of the
coated article. It is also desirable in certain embodiments for the
"k" value to be low in order to achieve good transmission. In
certain embodiments, the refractive index of coating 43 is from
about 1.4 to 2.0, more preferably no greater than about 1.75, and
most preferably from about 1.5 to 1.7. The refractive index n of
the coating can also be altered using CF.sub.4 or CF.sub.6 as the
doping gas. Fluorination of no more than about 5% atomic is
preferred. The table below shows variation of n & k with atomic
F content:
1 F % n @ 543 nm k @ 543 nm Eg(eV) 0 2.2 0.02 2.0 1.5 1.75 0.007
2.9 3.0 1.65 0.0001 3.7
[0078] Thus, fluorination provides a way in which to independently
tune the n & k to match desired optical properties of the
substrate 41 in order to improve transmission and the like.
Fluorination may also scavenge a graphitic sp.sup.2 fraction within
the carbon matrix thus leaving mostly sp.sup.3 enriched carbon
matrix.
[0079] A third ion beam source is optional. In certain embodiments
of this invention, the hydrophobicity of coating 43 can be further
enhanced using a plasma treatment by a third source or grafting
procedure after the main portion of DLC-inclusive coating 43 has
been deposited. This technique using a third source removes certain
polar functional groups at the outermost surface, thereby altering
the surface chemical reactivity (i.e. lowering surface energy)
while the bulk of coating 43 remains the same or substantially
unaffected. After a conveyor has moved the DLC-coated substrate
from the second source station to a position under the third
source, the plasma treatment by the third source introduces
hydrogen (H) atoms into the outermost surface of coating 43,
thereby making the coating's surface substantially non-polar and
less dense than the rest of the coating 43. These H atoms are
introduced, because H.sub.2 or ArH.sub.2 feedstock gas is used by
source 63 instead of the C.sub.2H.sub.2 gas. Thus, the third source
does not deposit any significant amounts of C atoms or Si atoms;
but instead treats the outermost surface of the ta-C:SiO coating by
adding H atoms thereto in order to improve its hydrophobic
characteristics. This plasma treatment may also function to roughen
the otherwise smooth surface. It is noted that H.sub.2 feedstock
gas is preferred in the third ion beam source when it is not
desired to roughen the surface of coating 43, while ArH.sub.2
feedstock gas is preferred in surface roughing embodiments.
Additionally, a CF.sub.4 RF induced plasma may be used to provide a
striation process with RMS roughness of at least about 100
angstroms (A).
[0080] Contact angle .theta. of coating 43 with water increases
with surface roughness as shown below, via certain examples
performed in accordance with certain embodiments of this
invention:
2 Sample No. Roughness RMS (A) Contact Angle .theta. 1 5
101.degree. 2 30 109.degree. 3 120 117.degree.
[0081] In certain alternative embodiments of this invention, the
third source may be used to introduce F atoms to the outermost 5 A
layer portion of coating 43 (in addition to or instead of the H
atoms) in order to reduce surface energy. Fluorination of no more
than about 5% (atomic percent) is preferred.
[0082] While in certain preferred embodiments of this invention,
three separate ion beam sources are used to make coated backlites
according to either of the FIGS. 5-6 embodiments, in alternative
embodiments it is recognized that a single ion beam source (linear,
curved, or the like) may be used to perform each of the cleaning
step, the deposition step of DLC-inclusive coating 43, and the
plasma surface treatment for introducing H and/or F atoms into the
outermost surface area of the coating. In such embodiments, the
feedstock gas may be changed between each such process.
ADDITIONAL EXAMPLE SAMPLE NOS. 1-3
[0083] Three additional example coated substrates were manufactured
and tested according to different embodiments of this invention as
follows. They are additional Sample Nos. 1-3, each including a
coating 43 according to an embodiment of this invention deposited
on glass using tetramethyl-silane (TMS) and O.sub.2 gas introduced
within the linear ion beam. All sample coatings 43 were of
approximately the same thickness of about 750 A. A low energy
electron flood gun was used to sharpen the spectral analysis
conducted by x-ray photo-electron spectroscopy (XPS) for chemical
analysis. In XPS analysis of a coating 43, high energy x-ray
photons (monochromatic) impinge on the surface of coating 43.
Electrons from the surface are ejected and their energy and number
(count) measured. With these measurements, one can deduce the
electron binding energy. From the binding energy, one can determine
three things: elemental fingerprinting, relative quantity of
elements, and the chemical state of the elements (i.e. how they are
bonding). Components used in the XPS analysis include the
monochromatic x-ray source, an electron energy analyzer, and
electron flood gun to prevent samples from charging up, and an ion
source used to clean and depth profile. Photoelectrons are
collected from the entire XPS field simultaneously, and using a
combination of lenses before and after the energy analyzer are
energy filtered and brought to a channel plate. The result is
parallel imaging in real time images. Sample Nos. 1-3 were made and
analyzed using XPS, which indicated that the samples included the
following chemical elements by atomic percentage (H was excluded
from the chart below).
3 Sample No. C O Si F 1 54.6% 23.7% 20.5% 1.2% 2. 45.7% 21.7% 32.7%
0% 3. 59.5% 22.7% 17.8% 0%
[0084] H was excluded from the XPS analysis because of its
difficulty to measure. Thus, H atoms present in the coating Sample
Nos. 1-3 were not taken into consideration for these results. For
example, if Sample No. 1 included 9% H by atomic percentage, then
the atomic percentages of each of the above-listed elements C, O,
Si and F would be reduced by an amount so that all five atomic
percentages totaled 100%.
[0085] In certain embodiments of this invention, coated backlites
13 have a contact angle .theta. of at least about 70.degree., more
preferably at least about 80.degree., and even more preferably at
least about 100.degree. after a taber abrasion resistance test has
been performed pursuant to ANSI Z26.1. The test utilizes 1,000
rubbing cycles of coating 43, with a load a specified in Z26.1 on
the wheel(s). Another purpose of this abrasion resistance test is
to determine whether the backlite is resistive to abrasion (e.g.
whether hazing is less than 4% afterwards). ANSI Z26.1 is hereby
incorporated into this application by reference.
[0086] Once given the above disclosure, many other features,
modifications, and improvements will become apparent to the skilled
artisan. Such other features, modifications, and improvements are,
therefore, considered to be a part of this invention, the scope of
which is to be determined by the following claims.
* * * * *