U.S. patent application number 13/453616 was filed with the patent office on 2012-10-18 for device having reduced friction properties.
Invention is credited to Peter Kracht, Marta Krzyak, Marten Walther.
Application Number | 20120263936 13/453616 |
Document ID | / |
Family ID | 43705929 |
Filed Date | 2012-10-18 |
United States Patent
Application |
20120263936 |
Kind Code |
A1 |
Krzyak; Marta ; et
al. |
October 18, 2012 |
DEVICE HAVING REDUCED FRICTION PROPERTIES
Abstract
A device, in particular a cover panel for a display device or a
monitor auxiliary panel or a surface for input devices, includes a
substrate and a coating applied onto the substrate. The coating has
a surface having a coefficient of friction in the range between
approximately 0.01 and 0.12, in particular between approximately
0.02 and 0.1, or between approximately 0.03 and 0.09.
Inventors: |
Krzyak; Marta; (Bad
Gandersheim, DE) ; Walther; Marten; (Alfeld, DE)
; Kracht; Peter; (Holzminden, DE) |
Family ID: |
43705929 |
Appl. No.: |
13/453616 |
Filed: |
April 23, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/EP2010/006397 |
Oct 20, 2010 |
|
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13453616 |
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Current U.S.
Class: |
428/304.4 ;
156/285; 428/336; 428/337; 428/426; 977/755 |
Current CPC
Class: |
Y10T 428/266 20150115;
F21V 3/04 20130101; C03C 2217/425 20130101; C03C 2217/76 20130101;
C23C 18/1225 20130101; C23C 18/1254 20130101; Y10T 428/265
20150115; C03C 17/3417 20130101; C23C 18/1216 20130101; C03C
2217/734 20130101; C03C 17/42 20130101; G02B 1/115 20130101; C03C
2218/365 20130101; Y10T 428/249953 20150401 |
Class at
Publication: |
428/304.4 ;
156/285; 428/336; 428/426; 428/337; 977/755 |
International
Class: |
B32B 17/06 20060101
B32B017/06; B32B 5/00 20060101 B32B005/00; B32B 3/26 20060101
B32B003/26; B32B 37/10 20060101 B32B037/10; B32B 37/14 20060101
B32B037/14 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2009 |
DE |
10 2009 050 568.7 |
Claims
1. A cover panel for one of a display device, a monitor front panel
and a surface for inputs, the cover panel comprising: a substrate
which is a substantially flat panel having a first side and a
second side; and a coating applied onto at least one of said first
side and said second side of said substrate to form an entire
system, said coating including at least one anti-reflective coating
and a cover layer arranged over said anti-reflective coating, a
surface of said cover layer having a coefficient of friction in a
range between approximately 0.01 and 0.12 and a reflectivity of
said entire system being between approximately 0.1% and 7%.
2. The cover panel according to claim 1, wherein said coefficient
of friction is in a range between approximately 0.02 and 0.1.
3. The cover panel according to claim 2, wherein said coefficient
of friction is in a range between approximately 0.03 and 0.09.
4. The cover panel according to claim 1, wherein said coating is
formed of a material selected to substantially avoid adherence of a
plurality of organic substances.
5. The cover panel according to claim 4, wherein said plurality of
organic substances include a plurality of oils and skin oil.
6. The cover panel according to claim 1, wherein said cover layer
has a thickness <approximately 20 nanometers (nm).
7. The cover panel according to claim 6, wherein said cover layer
has a thickness less than approximately 10 nm.
8. The cover panel according to claim 7, wherein said cover layer
has a thickness in a range between approximately 0.1 nm to 10
nm.
9. The cover panel according to claim 1, wherein said at least one
anti-reflective coating is optically adapted to said cover layer to
provide an anti-reflective effect.
10. The cover panel according to claim 1, wherein a refractive
index of said coating between said cover layer is in a range
between approximately 1.37 and 1.6.
11. The cover panel according to claim 1, wherein said substrate is
one of a glass panel, a synthetic substrate and a laminated glass
panel.
12. The cover panel according to claim 11, wherein said glass panel
is one of a soda-lime glass panel and a borosilicate glass panel
obtained in one of a draw method, float technology, from cast glass
and from rolled glass.
13. The cover panel according to claim 11, wherein said synthetic
substrate is an acrylic-glass substrate.
14. The cover panel according to claim 1, wherein said substrate
has a thickness in a range between approximately 0.05 millimeters
(mm) and 10 mm.
15. The cover panel according to claim 14, wherein said substrate
has a thickness in a range between approximately 0.05 mm and 8
mm.
16. The cover panel according to claim 15, wherein said substrate
has a thickness in a range between approximately 0.05 to 3 mm.
17. The cover panel according to claim 1, wherein an outward facing
surface of said coating has an angle of contact of
>approximately 50.degree..
18. The cover panel according to claim 17, wherein said angle of
contact is approximately 70.degree..
19. The cover panel according to claim 18, wherein said angle of
contact is >approximately 80.degree..
20. The cover panel according to claim 1, wherein said reflectivity
of said entire system is in a range between approximately 0.1% and
6%.
21. The cover panel according to claim 20, wherein said
reflectivity of said entire system is in a range between
approximately 0.1% and 5.5%.
22. The cover panel according to claim 21, wherein said
reflectivity of said entire system is in a range between
approximately 0.1% and 4%.
23. The cover panel according to claim 22, wherein said
reflectivity of said entire system is in a range between
approximately 0.1% and 2%.
24. The cover panel according to claim 23, wherein said
reflectivity of said entire system is in a range between
approximately 0.1% and 1.5%.
25. The cover panel according to claim 1, wherein said at least one
anti-reflective coating is applied using one of a liquid
technology, a high-vacuum technology, a chemical vapor deposition
(CVD) process, and an etching process.
26. The cover panel according to claim 25, wherein said liquid
technology is a sol-gel technology.
27. The cover panel according to claim 26, wherein said at least
one anti-reflective coating is one of a single-layer interference
coating and a multi-layer interference coating.
28. The cover panel according to claim 27, wherein said multi-layer
interference coating is a three layer to seven layer interference
coating.
29. The cover panel according to claim 28, wherein said multi-layer
interference coating is a three-layer interference coating
including a first layer having a refractive index between
approximately 1.6 and 1.8, a second layer having a refractive index
between approximately 1.9 and 2.5, and a third layer having a
refractive index between approximately 1.4 and 1.5.
30. The cover panel according to claim 25, wherein said at least
one anti-reflective coating is applied using said high-vacuum
technology as one of a single layer system and a multi-layer
interference coating system.
31. The cover panel according to claim 30, wherein said multi-layer
interference coating system includes a three-layer to a seven-layer
interference coating.
32. The cover panel according to claim 31, wherein said at least
one anti-reflective coating is produced in a sputtering process
under a high vacuum.
33. The cover panel according to claim 31, wherein said at least
one anti-reflective coating is produced in a high-vacuum process
using thermal evaporation.
34. The cover panel according to claim 25, wherein said CVD process
is one of an online-CVD process and an offline-CVD process.
35. The cover panel according to claim 25, wherein said at least
one anti-reflective coating is applied using said etching process
as one of a porous layer and a light-scattering surface.
36. The cover panel according to claim 1, wherein the cover panel
is used for one of a display device, a part of a touch panel, a
part of a touch screen with optical scanning, within a display
system as a touch panel for interactive input of a plurality of
signals, as a cover panel, as a protective panel, and as a
protective cover for at least one of a display, an information
display unit and a touch screen.
37. A method to produce a cover panel for one of a display device,
a monitor front panel, and a surface for inputs, the method
comprising the steps of: providing a substrate; applying an
anti-reflective coating onto said substrate according to one of a
liquid technology and a high-vacuum technology; introducing said
coated substrate into a pressure vessel set to a vacuum in a range
of between approximately 10 Pascals (Pa) to 1050 hectopascals
(hPa); and applying a cover layer onto said anti-reflective coating
such that a coefficient of friction is between approximately 0.01
and 0.12.
38. The method according to claim 37, wherein said liquid
technology is a sol-gel technology.
39. The method according to claim 37, wherein said pressure vessel
is set to between approximately 10 hPa to 500 hPa.
40. The method according to claim 37, wherein said vacuum is one of
a fine vacuum in a range between approximately 10 Pa and 100 Pa and
a low vacuum above 100 Pa, said vacuum being evacuated.
41. The method according to claim 37, wherein said coefficient of
friction is between approximately 0.02 and 0.1.
42. The method according to claim 41, wherein said coefficient of
friction is between approximately 0.03 and 0.09.
43. The method according to claim 37, further comprising the step
of putting an ultra-hydrophobic coating material into a vaporizer
located in said pressure vessel and evaporating and subsequently
precipitating said ultra-hydrophobic coating material onto a
surface of one of said substrate and said coating such that said
one of said substrate and said coating has a coefficient of
friction between approximately 0.01 and 0.12.
44. The method according to claim 43, wherein said
ultra-hydrophobic coating material is precipitated onto said at
least one anti-reflective coating in a form of said cover
layer.
45. The method according to claim 43, wherein said coefficient of
friction is between approximately 0.02 and 0.1.
46. The method according to claim 45, wherein said coefficient of
friction is between approximately 0.03 and 0.09.
47. The method according to claim 43, wherein a temperature in said
vaporizer is between approximately 100.degree. C. and 400.degree.
C.
48. The method according to claim 47, wherein said substrate
exhibits a temperature of between approximately 300 K and 370
K.
49. The method according to claim 37, wherein said cover layer has
a thickness <approximately 20 nanometers (nm).
50. The method according to claim 49, wherein said thickness of
said cover layer is <approximately 10 nm.
51. The method according to claim 50, wherein said thickness of
said cover layer is in a range between approximately 0.1 nm to 10
nm.
51. The method according to claim 37, further comprising the step
of producing one of a display device, a part of a touch panel, a
part of a touch screen with optical scanning, a touch panel within
a display system for interactive input of a plurality of signals, a
cover for a display system for interactive input of a plurality of
signals, a protective panel for a display system for interactive
input of a plurality of signals, a protective cover for a display,
an information display unit, and a touch screen.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of PCT application No.
PCT/EP2010/006397, entitled "DEVICE HAVING REDUCED FRICTION
PROPERTIES", filed Oct. 20, 2010, which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a device, in particular to
a cover panel for a display device or a monitor front panel or a
surface for inputs including a substrate and a coating applied onto
the substrate, use of such a device, as well as a method to produce
such a device.
[0004] 2. Description of the Related Art
[0005] From DE 198 48 591 A1 an optical glass panel has become
known which is provided with a fluoro-organic compound. According
to DE 198 48 591 A1, through the coating with a fluoro-organic
compound, glass panels, in particular wind shields, window panes or
headlight lenses of vehicles are provided which distinguish
themselves through high scratch resistance, reduced air friction,
improved sliding of windshield wipers as well as dirt repellence.
DE 198 48 591 A1 is restricted to the field of conventional glass
panels. In particular the importance of avoiding fingerprints in
the field of display panels is not described.
[0006] A special coating system for a substrate has become known
from U.S. Pat. No. 6,472,017 B2 which includes a diamond-like
carbon layer and one layer of fluoro-alkyl-silane. The diamond-like
carbon layer provides durability and/or hydrophobicity. The
fluoro-alkyl-silane layer also serves to provide a high contact
angle of the coating system. U.S. Pat. No. 6,472,017 B2 also does
not describe avoidance of finger prints.
[0007] From DE 10 2007 058 927 A1 a substrate comprising a
sol-gel-layer and a barrier layer as well as an anti-reflective
layer has become known. The anti-reflective layer can be applied in
the sol-gel-process. The coating described in DE 10 2007 058 927 A1
finds use as an abrasion resistant laminate material in the field
of solar cells. Coefficients of friction, in particular values of
the initial friction, are not described in DE 10 2007 058 927
A1.
[0008] From DE 39 41 797 A1 a coating system with a high
anti-reflective effect for a substrate has become known, whereby
the coating is applied with the assistance of chemical vapor
deposition (CVD) or reactive sputtering. Further, DE 102 13 036 A1
describes the coating of a synthetic film with a multi-layer
interference coating, whereby the multi-layer interference coating
can also find use for an anti-reflection system. Neither in DE 30
41 797 A1 nor in DE 102 13 036A1 are coefficients of friction
stated for the coating systems.
[0009] Coated substrates, according to those described above often
have the problem that the surfaces of these coatings are often very
rough in spite of high contact angles. This results in that glass
panels, which for example find use in the field of displays, are
scratched by ball pens or pens which leads to an unsteady character
image and in addition affects the surface. Especially in the use of
glass panels in display products which include a touch-panel
application, namely a surface whereby through touching of certain
areas of the surface the program sequence of a technical device can
be directly controlled, the top (glass) surface and its properties
is important. However, due to the previously cited problems
according to the current state of the art the top glass surface was
not able to recognize writing with certainty.
[0010] Moreover, the glass surfaces according to the current state
of the art were susceptible to contamination for example through
finger prints. Therefore, according to the current state of the
art, cleaning solutions containing professional and commercial
glass cleaning agents had to be used to clean the glass
surfaces.
[0011] What is needed in the art is a device which can be used for
example for touch-panel applications which is dirt repellent and
scratch resistant. Fingerprints in particular should be avoided as
far as possible on the surface, or should be visible as little as
possible.
SUMMARY OF THE INVENTION
[0012] The present invention provides a device including a
substrate, as well as a coating applied onto the substrate, wherein
the coating on the surface exhibits a a coefficient of friction
(tan .alpha.) in the range between approximately 0.01 and 0.12, for
example between 0.02 and 0.1, or between 0.03 and 0.09. The
coefficient of friction is a coefficient of friction which is
determined on a slanted plane which is tilted at an angle .alpha..
Angle .alpha. at which a weight arranged on the plane will slide
determines the coefficient of friction. The coefficient of friction
according to the current invention is a coefficient of friction of
rest or static friction or a starting coefficient of friction, in
contrast to the coefficient of sliding friction or dynamic
coefficient of friction.
[0013] The inventive coating ensures that the surface appears
smooth, or respectively is smoothed, and that the coefficient of
friction of the surface of the substrate is reduced.
[0014] If a surface is provided with a coating according to the
present invention, then it is, for example, possible to move an
input device on this surface without "scratching" or undesirable
"sticking", as is typically the case, for example, with a pen
having a synthetic tip or a finger on normal glass surfaces.
Moreover, the adherence of dirt or fingerprints on the surface is
substantially reduced, so that dry cleaning of these contaminants
on a surface with reduced adhesion is possible. This is especially
advantageous with touch-panel applications.
[0015] In addition, the adherence, or respectively sticking of
organic substances, for example oils, such as skin oil, is
substantially reduced or respectively practically completely
prevented on a substrate provided with the inventive coating, so
that fingerprints are largely avoided or respectively are far less
visible. Since the skin oil adheres less or practically not at all
on the coating, cleaning of the substrate with an inventive coating
is also easier. In one embodiment of the present invention the
contaminations from organic substances or respectively skin oil can
even be wiped off dry. This means that, for example on displays or
touch screen panels, the obligatory cleaning agents for organic
contaminants can be relinquished.
[0016] According to an embodiment of the present invention the
coating includes an anti-reflective coating. The coating including
the anti-reflective coating or respectively the anti-reflection
coating has, for example, a coefficient of friction (tan .alpha.)
or respectively a static coefficient of friction on the surface in
the range of between approximately 0.01 and 0.12, for example
between 0.02 and 0.1, or between 0.03 and 0.09. As a rule this is
achieved by a cover layer applied on the anti-reflective or
respectively anti-reflection coating. The thickness of the cover
layer which reduces the coefficient of friction is in the range of
between 0.1 nanometers (nm) to 10 nm.
[0017] The substrate is, for example, a glass panel, such as a
soda-lime glass panel or a borosilicate glass panel which is
obtained, for example in a draw method, for example up-draw or
down-draw method, or in the float technology or from a cast glass
or rolled glass. In particular with the latter method, namely the
cast or roll method it is feasible that the necessary optical
quality of the surface may be obtained through a polishing method
which is required, for example, for a display front panel. The
substrate may alternatively also be a synthetic substrate.
[0018] For application in display glasses, such as touch-panels or
touch screens of small formats the substrate is, for example
.ltoreq.1 mm thick and is an ultra-thin substrate. Exemplary
materials are the ultra-thin glasses D263, B270 or Borofloat by
SCHOTT AG.
[0019] If the devices are used for cover panels for displays,
optionally also as touch-panels or touch screens, for larger
surfaces, for example surfaces larger than 1 square meter
(m.sup.2), then substrates having a thickness of between
approximately 4 to 6 millimeters (mm) are used, so that a
mechanical protective function of the displays is also assumed.
[0020] The panels can be single panels as well as laminated panels.
A laminated panel for example includes two panels, a first and a
second panel, which are laminated for example with a polyvinyl
butyral (PVB) film. Of the outward facing surfaces of the laminated
panel at least one surface is provided with an inventive, friction
reduced surface having a coefficient of friction or respectively a
static coefficient of friction (tan .alpha.), in the range of
between approximately 0.01 and 0.12, for example between 0.02 and
0.1 or between 0.03 and 0.09.
[0021] In order to provide not only extreme smoothness of the
surface, but also a surface which can be easily cleaned with liquid
cleaning agents, the inventive layers have contact angles
>approximately 50 degrees, for example >70 degrees. Layers
having contact angles >50 degrees, for example >70 degrees
allow, in addition to the previously described dry cleaning, simple
cleaning of the glass surface from contaminants using liquid
cleaning agents such as glass cleaners or water. The reduced
adherence mechanism which, for example is distinguished by a low
coefficient of friction, is substantially responsible for the good
cleanability, in particular dry cleaning of the inventive layers or
respectively coatings. The inventive layer or respectively coating
however, also has a high contact angle which can even reach more
than 100.degree.; however decisive for the dry-cleanability is the
low adherence of contaminants, such as organic contaminants on the
surface of the coating, and not the high angle of contact.
[0022] The primary application for the herein described devices
with a substrate and a coating applied thereto, having a low
coefficient of friction is in the use of a cover panel providing a
mechanical protective function and/or a surface for inputs, for
example input devices or so-called displays. The device finds use
in areas where technical devices can be operated by touching of
parts on the surface of the device, namely in the area of
touch-panel applications with interactive input. Since a panel of
this type also introduces additional interfaces into the total
optical system of the display, a reflectivity of approximately 8%
is achieved on the display when using only a conventional float
glass panel as substrate material without anti-reflective coating.
This reflectivity interferes with the effective contrast of the
display since reflections compete with the useful signal of the
display. For this reason, it is especially advantageous for this
application to incorporate an anti-reflective coating or
respectively an anti-reflection coating onto the substrate, namely
to use a panel provided with an anti-reflective coating, whose
reflectivity R.sub.VIS clearly reduces in the visible wavelength
range at standard light D65 and is, for example lower than
approximately 4%, or <2%. This glass or synthetic panel then
includes an anti-reflective coating which is also referred to as
anti-reflection coating and which is applied according to one of
the following application methods: [0023] a) The anti-reflective
coating or respectively the anti-reflection coating is applied with
the assistance of liquid technology, whereby the coating applied
with the assistance of the liquid technology is provided with the
assistance of one of the following techniques: [0024] The
anti-reflective coating is applied using the sol-gel technology;
[0025] The anti-reflective coating is produced as single-layer
interference coating in the sol-gel-technology; [0026] The
anti-reflective coating is produced as multi-layer interference
coating in the sol-gel technology, wherein the multi-layer
interference coating is, for example, a three- to seven-layer
interference coating; or [0027] The anti-reflective coating is
produced as a three-layer interference coating in the sol-gel
technology, whereby the first layer has a refractive index between
approximately 1.6 and 1.8, the second layer has a refractive index
between approximately 1.9 and 2.5 and the third layer has a
refractive index between approximately 1.4 and 1.5. [0028] b) The
anti-reflective coating or respectively anti-reflection coating is
produced with the assistance of a high-vacuum technology, whereby
the coating applied with the assistance of high-vacuum technology
is provided in one of the following techniques: [0029] The
anti-reflective coating is produced with the assistance of a
high-vacuum technology as a multi-layer interference coating
system, wherein the multi-layer interference coating is, for
example, a three-layer to seven-layer interference coating; [0030]
The anti-reflective coating is produced with the assistance of a
high-vacuum technology as a single layer system; [0031] The
anti-reflective coating is produced in a sputtering process under
high vacuum; or [0032] The anti-reflective coating is produced in a
high-vacuum coating process by thermal evaporation; [0033] c) The
anti-reflective coating or respectively anti-reflection coating is
produced with the assistance of a CVD process, whereby the layer
applied with the assistance of a CVD process is provided in one of
the following techniques: [0034] The anti-reflective coating is
produced in an online-CVD process; or [0035] The anti-reflective
coating is produced in an offline-CVD process; [0036] d) The
anti-reflective coating or respectively anti-reflection coating is
produced with the assistance of an etching process, whereby the
layer applied with the assistance of an etching process is provided
in one of the following techniques: [0037] The anti-reflective
coating is produced with the assistance of an etching process as a
porous layer; or [0038] The anti-reflective coating is produced
with the assistance of an etching process as a light-scattering
surface.
[0039] If an anti-reflective coating is applied, and the
anti-reflective coating is provided with a cover layer which has a
static coefficient of friction (tan .alpha.) in the range between
approximately 0.01 and 0.12, for example between 0.02 and 0.1, or
between 0.03 and 0.09, then the anti-reflective coating is
optically adapted to the cover layer, for example through addition
of precursor materials or polymers, so that an anti-reflective
effect is provided. The anti-reflective effect is such that, with
one- or two-sided application the reflectivity of the entire system
is between approximately 0.1% and 7%, for example between 0.1% and
6%, between 0.1% and 5.5%, between 0.1% and 4%, between 0.1% and
2%, or between 0.1% and 1.5% in the visible wavelength range at
standard light D65.
[0040] According to one embodiment of the present invention, the
substrate with coating is used in one of the following areas or for
one of the following products: [0041] a protective cover for
displays or respectively display devices; [0042] a cover panel for
displays; [0043] a cover panel for touch panels, [0044] a part of
the touchscreen with optical scanning; or [0045] within a display
system as a touchpad for interactive input of signals, or as cover
or protective panel.
[0046] In addition to the device, the present invention also
provides a method to produce a coating having a coefficient of
friction between approximately 0.01 and 0.12, for example between
0.02 and 0.1, or between 0.03 and 0.09 on a substrate which,
includes the following steps: [0047] A coating, in particular an
anti-reflection coating is applied according to a liquid
technology, such as with sol-gel technology, or with high-vacuum
technology onto a substrate; [0048] The coated substrate is
introduced into a pressure vessel which is evacuated at low vacuum;
[0049] The coating applied onto the substrate is processed in a
further step, for example smoothed locally in such a way that the
coefficient of friction is between approximately 0.01 and 0.12, for
example between 0.02 and 0.1, or between 0.03 and 0.09.
[0050] According to a second embodiment of the method according to
the present invention: [0051] The coated substrate is introduced
into a pressure vessel which is set to a vacuum in the range of
between approximately 10 Pascals (Pa) to 1050 hectopascals (hPa),
for example between 10 hPa to 500 hPa, wherein for example a vacuum
in the form of a fine vacuum in the range between 10 Pa and 100 Pa
or a low vacuum above 100 Pa is evacuated; [0052] A cover layer is
applied onto the coating in such a manner that the coefficient of
friction is between approximately 0.01 and 0.12, for example
between 0.02 and 0.1, or between 0.03 and 0.09. The coating is
hereby for example smoothed, at least locally.
[0053] In order to adjust the coefficient of friction the
ultra-hydrophobic coating material "Duralon Ultratec" produced by
Cotec GmbH., Frankenstra.beta.e 19, D-63791, Karlstein, Germany can
for example, in the form of a tablet (14 mm diameter, 5 mm height)
be put into a vaporizer which is located in the aforementioned
pressure vessel. From this vaporizer the coating material is then
evaporated from the filling of the tablet at temperatures of
between approximately 100.degree. C. to 400.degree. C. and
precipitates onto the surface of the substrate or onto a previously
applied coating, for example onto an anti-reflection coating or
respectively anti-reflex coating as a cover layer. For distribution
of the coating material a device for general coating of objects is
used, as disclosed in EP-A-1816232, the disclosure content of which
is incorporated into the current application in its entirety. The
time- and temperature profiles are set as provided by Cotec GmbH,
FrankenstraBe 19, D-63791, Karlstein, Germany for evaporation of
the "Duralon Ultratec" material tablet. The substrates (non-coated
and/or with anti-reflection coating) reach a slightly elevated
temperature during the process which is in the range of between
approximately 300K to 370K.
[0054] The previously described application method normally
delivers cover layers which are only a few nm thick, generally less
than approximately 10 nm thick and, for example, represent only a
monomolecular saturation of the surface of the coating or
respectively the substrate. If cover layers are applied onto
anti-reflective coatings or respectively anti-reflection coatings,
the thickness of the coating or the refractive index of the entire
system consisting of coating and cover layer changes. In order to
continue to receive good anti-reflection, the entire system
consisting of anti-reflective coating and cover layer may be
adapted. Since the cover layer is very thin, the optical system
with an anti-reflection coating only needs to be adjusted slightly
with such thin cover layers, in order to achieve the desired tint
of the residual reflection of the anti-reflection coating, for
example by altering the layer structure. It is known to the expert
how admixtures can be added to the process described above which
effect for example a layer thickness of higher than approximately
10 nm for the anti-reflection coating. An example which can be
mentioned is, that simultaneously with the evaporation of the layer
having low static friction, an additional polymer compound which
leaves behind a transparent layer may be evaporated. The material
to reduce the static friction is then incorporated into this layer
and can achieve clear optic effect as a layer of more than
approximately 10 nm.
[0055] In this case the uppermost cover layer including for
example, a material having a low coefficient of friction, as well
as the last layer adjacent to the cover layer of the
anti-reflection system including low refractive material having a
refractive index between approximately 1.37 and 1.6 should be
considered as a single layer, which is calculated together into the
configuration of the anti-reflection system. As admixtures for the
cover layer, diverse materials in addition to the aforementioned
polymers can be used as precursors for known CVD processes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] The above-mentioned and other features and advantages of
this invention, and the manner of attaining them, will become more
apparent and the invention will be better understood by reference
to the following description of embodiments of the invention taken
in conjunction with the accompanying drawings, wherein:
[0057] FIG. 1 illustrates the principle of measurement to determine
the coefficient of friction; and
[0058] FIGS. 2a-2b illustrate the device according to the present
invention, including a single flat panel as the substrate material
(FIG. 2a) and a laminated panel (FIG. 2b).
[0059] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplifications set out
herein illustrate one embodiment of the invention and such
exemplifications are not to be construed as limiting the scope of
the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0060] Referring now to the drawings, and more particularly to FIG.
1, there is shown the principle of measurement for the coefficient
of friction as is the basis for the current invention and as stated
in table 1 for various samples. A glass panel to be tested,
provided with a coating is brought into a defined slanted position
and is moved through movable stop 14 over the edge of block 12,
having a height a in direction 15 so that the angle of the slant,
angle .alpha. becomes increasingly larger. When moving stop 14,
distance b between support point 17 and block 12 changes, thereby
changing angle .alpha.. The height of block 14 is 15 mm. The
following equation applies to angle .alpha.:
tan(.alpha.)=a/b
[0061] Weight 20 resting on the pane starts to slide with
increasing angle .alpha.. The angle at which weight 20 starts to
slide on the glass pane is then the measure for the coefficient of
friction according to the present invention. The coefficient of
friction according to the present invention is hereby the
coefficient of friction of rest, or starting coefficient of
friction or a coefficient of static friction. As weight 20 a
"Delrin" (POM) cuboid measuring 20.times.20.times.10 mm with
applied brass piece and a total weight of 106 g is, for example
used. Angle .alpha. can be determined very simply from distances b
and a, as described above. At fixed height .alpha. and
determination of length b at which the block starts to slide, angle
.alpha. which is consistent with the coefficient of friction, in
this case the coefficient of static friction, can be
determined.
[0062] Measurements were taken of the following tests and, as shown
in table 1, the coefficient of friction and the angle of contact
determined for the examples:
Example 1
Sample 1
[0063] In the trial according to sample 1 the anti-reflection
coating was produced according to the sol-gel method. The coating
includes three individual layers respectively and possesses the
following structure: Substrate+M+T+S.
[0064] The individual layer identified with T contains titanium
dioxide (TiO.sub.2). The individual layer identified with S
contains silicon dioxide (SiO.sub.2) and the individual layer
identified with M is always drawn from S and T mixed solutions. The
float glass substrate is carefully cleaned prior to coating. The
dipping solutions are respectively applied in rooms which are
air-conditioned to approximately 28.degree. C. at a humidity of 5
to 10 grams per kilogram (g/kg), whereby the draw speeds for each
individual layer M/T/S are approximately 275/330/228 millimeters
per minute (mm/min). Drawing of each gel layer is followed by a
curing process in air. The curing temperature and the curing time
are approximately 180.degree. C./20 min after production of the
first gel layer, as well as approximately 440.degree. C./60 meter
(m) after production of the second and third gel layer. In the case
of the T-layers the dipping solution (per liter) includes the
following: approximately 68 milliliters (ml) titanium-M-butylate,
approximately 918 ml ethanol (ABS), approximately 5 ml acetyl
acetone and approximately 9 ml ethyl-butyl-acetate.
[0065] The dipping solution to produce the S-layer includes:
approximately 125 ml silicic acid methyl ester, approximately 400
ml ethanol (ABS), approximately 75 ml H.sub.2O (distilled),
approximately 7.5 ml acetic acid and is diluted with approximately
393 ml ethanol (ABS) after a rest period of approximately 12 hours.
The coating solutions to produce the oxides with the medium
refractive index are prepared by mixing of the S+T solutions. The
layer identified with M is drawn from a dipping solution having a
silicon dioxide content of approximately 5.5 grams per liter (g/l)
and a titanium dioxide content of approximately 2.8 g/l. The
applied wet-chemical sol-gel process permits economic dip-coating
of large areas.
[0066] In addition to the anti-reflection coatings produced with
the assistance of the sol-gel method (sample 1), anti-reflection
coatings can also be applied with the assistance of sputtering
processes. Such a coated system is shown below.
Example 2
Sample 2
[0067] The example-sample 2 is a one-sided anti-reflection coating
which is applied as follows in the sputtering process: The coating
is deposited in an inline unit in a mid-frequency (MF) sputtering
process through magnetron sputtering, whereby the substrate is
positioned on a so-called carrier and is transported on same
through the sputtering unit. The application method is as follows:
[0068] a) Inside the coating unit the substrate is first "heated to
approximately 150.degree. C. for dewatering of the surface". Then
an anti-reflection system (for example including four layers) is
produced as follows: [0069] b) Sputtering of a high refractive
substrate at a feed rate of approximately 1.7 meters per minute
(m/min), whereby the carrier oscillates in front of the sputtering
source and while the layer of 30 nm thickness is deposited. The
production of the layer occurs through addition of argon and
reactive gas, by regulating the reactive gas to plasma impedance.
The process pressure is determined in particular through the amount
of argon, which leads to typical process pressures in the range
between 1.times.E-3 and 1.times.E-4 millibar (mbar). The deposition
in the plasma occurs through pulsation. [0070] c) Sputtering of a
low refractive layer at a feed rate of approximately 2.14 m/min. A
layer having a thickness of approximately 30.5 nm is hereby
produced. The layer production occurs according to the deposition
described for layer 1. [0071] d) Sputtering of a high refractive
layer according to layer 1. Here, a layer having a thickness of
approximately 54 nm is produced at a feed rate of approximately 0.9
m/min. [0072] e) Sputtering of a low-refractive layer according to
layer 2. A layer having a thickness of approximately 103 nm is
produced at a feed rate of approximately 0.65 m/min. Subsequently
the coated substrate is transferred out with the carrier through a
transfer chamber. [0073] f) To produce the sample the backside of
the sample was subsequently also provided with an anti-reflective
coating in a second coating passage according to steps a) through
d).
[0074] In addition layers which are coated according to example
sample 1 can be coated with ETC (easy to clean) layers.
[0075] Such systems are described in sample 3.
Example 3
Sample 3
[0076] A layer according to sample 1 is pre-cleaned in a washing
machine and pre-treated with a neutralizer so that the coating is
fat free. The thus cleaned surface is sprayed with the product
ClearShield which is offered commercially for example by Fa. Bohle
in Haan (Germany) and which represents a typical fluoro-polymer
solution for ETC (Easy To Clean) applications. The surface sprayed
with ClearShield is left to react at room temperature for
approximately 10 to 15 minutes. The coated surface is then washed
and dried. Through the coating with an ETC (easy to clean)
ClearShield layer the contact angle can be substantially improved
compared to untreated samples, as in sample 1 or 2. However, an
increase of the contact angle by 23 or respectively 46 degrees in
sample 1 or respectively sample 2 to 78 degrees in sample 3 does
not mean that the respective coefficient of friction is achieved
and that therefore a finger or pen can glide more easily over the
surface or that a dry cleaning is made possible.
[0077] In order to achieve this it is necessary according to the
present invention to provide a secondary treatment to the layer
according to sample 1 or respectively as previously described to
apply a cover layer as a smooth layer onto the anti-reflection
coating. This is cited in sample 4.
Example 4
Sample 4
[0078] The coating cited in sample 4 is again a coating in
accordance with sample 1 which is subjected to a secondary
treatment. In the secondary treatment the coating according to
sample 1 is after-treated in a process with vacuum. Here, the
coated glasses according to sample 1 are brought into a pressure
vessel which is subsequently evacuated with low vacuum.
[0079] In order to implement reduction of the coefficient of
friction or respectively smoothing of the coating, for example with
a cover layer, the ultra-hydrophobic coating material "Duralon
Ultratec" produced by Cotec GmbH., Frankenstra.beta.e 19, D-63791,
Karlstein, Germany can for example, in the form of a tablet (14 mm
diameter, 5 mm height) be put into a vaporizer which is located in
the aforementioned pressure vessel. From this vaporizer the coating
material is then evaporated from the filling of the tablet at
temperatures of between approximately 100.degree. C. to 400.degree.
C. and precipitates onto the surface of the substrate or onto a
previously applied coating, for example onto an anti-reflection
coating as a cover layer. For distribution of the coating material
a device for general coating of objects is used, as disclosed in
EP-A-1816232, the disclosure content of which is incorporated into
the current application in its entirety. The time- and temperature
profiles are set as provided by Cotec GmbH, Frankenstra.beta.e 19,
D-63791, Karlstein, Germany for evaporation of the "Duralon
Ultratec" material tablet. The substrates (non-coated and/or with
anti-reflection coating) reach a slightly elevated temperature
during the process which is in the range of between approximately
300K to 370K.
[0080] As can be seen in table 1, a coefficient of friction or
respectively a coefficient of static friction of tan .alpha.=0.07,
which is in the range of between approximately 0.01 to 0.12, is
achieved. As can further be seen in table 2, the angle of contact
for sample 4 is high, namely more than 100 degrees. It can further
be seen in table 1 that a coefficient of friction or respectively a
coefficient of static friction of 0.07, namely of between
approximately 0.01 and 0.12 is achieved, whereas the samples which
were not treated with an additional cover layer--sample 1 through
sample 3--have coefficients of friction or respectively
coefficients of static friction of approximately 0.16 through
0.2.
[0081] The results of the examination of the coefficients of
friction and angles of contact are given in the following
tables.
TABLE-US-00001 TABLE 1 coefficients of friction for sample
examples: Sample 1-Sample 4 1 2 3 4 5 1 2 3 4 5 Sample Distance
b/mm Coefficient of friction (tan .alpha.) Mean value Diffusion
Sample 1 cleaned 95 90 90 95 60 0.16 0.17 0.17 0.16 0.25 0.18 0.04
Sample 2 cleaned 90 80 90 100 90 0.17 0.19 0.17 0.15 0.17 0.17 0.01
Sample 3 cleaned 100 95 90 90 90 0.15 0.16 0.17 0.17 0.17 0.16 0.01
Sample 4 cleaned 190 210 260 250 250 0.08 0.07 0.06 0.06 0.06 0.07
0.01
[0082] The coefficients of friction or respectively the
coefficients of static friction were, as described above,
determined through determination of tan(.alpha.) by moving the
glass pane over a block having height a of, for example,
approximately 15 mm.
[0083] The results concerning the angle of contact are provided in
table 2.
TABLE-US-00002 TABLE 2 Angle of contact [.degree.] Sample Mean
value Diffusion Sample 1 23 0.63 Sample 2 46 1.67 Sample 3 78 1.02
Sample 4 107 0.40
[0084] For the angle of contact measurements samples were cleaned
on both sides using ethanol. Then the angle of contact was measured
using device PCA 100M/4 by DataPhysics. The method was implemented
as a static angle of contact measurement according to the Sessile
Drop method with deionized water and a drop volume of 3.5
microliters (.mu.l). 5 measurements were conducted for evaluation
purposes and the median value from the 5 measurements was
subsequently given as the measured value.
[0085] Referring now to FIGS. 2a and 2b, there is shown a layer
system according to the invention. The illustrated layer system
according to FIG. 2 includes substrate 100 in the form of a single
panel as well as coating 110 applied onto one side 114.1, including
anti-reflection coating 121.1 onto which in the current example
also cover layer 122 is applied as in example 4 (sample 4). Cover
layer 122 has a coefficient of friction in the range of between
approximately 0.01 to 0.12, for example between approximately 0.02
and 0.1, or between approximately 0.03 and 0.09 on outward facing
surface 112. This results in that a finger or pen can glide more
easily over the surface of such a sample, which is advantageous in
particular in applications in the field of touchscreens or
displays.
[0086] In particular adherence of organic contaminants, such as
skin oil is reduced. Fingerprints on the touchscreen or
respectively the display are thereby prevented and related cleaning
is facilitated including dry cleaning.
[0087] On the other side, namely the opposite side, such as the
backside 114.2 of substrate 100, second anti-reflection layer 121.2
may be provided in such a manner that a very low reflectivity of
R.sub.VIS<approximately 4%, for example <2% is achieved.
Technically relevant is hereby reflectivity R.sub.VIS>0.2%. This
means that the reflectivity R.sub.VIS in the visible wavelength
range at standard light D65 for the entire system is in the range
between approximately 4% and 0.2%, for example between
approximately 2% and 0.2%. The anti-reflection coating is often
also referred to as anti-reflective coating.
[0088] The substrate is, for example, a single glass panel, such as
a soda-lime glass panel or a borosilicate glass panel which is
obtained, for example, in a draw method, for example an up-draw or
down-draw method or in the float technology or from a cast glass or
rolled glass. With the latter method, namely the cast or roll
method, it is feasible that the necessary optical quality of the
surface is obtained through a polishing method which is required,
for example, for a display front panel.
[0089] As an alternative to the single panel the layer system, as
illustrated in FIG. 2b may also include a laminated panel as the
substrate. The same components as shown in FIG. 2a are identified
with same reference numbers. Substrate 100 includes as laminated
panel 205 first panel 2101.1 and second panel 210.2. First and
second panel 210.1, 210.2 are laminated to a lamination using film
211, for example a polyvinyl butyral (PVB) film. At least one
outward facing surface 212.1 and 212.2 of first panel 210.1 or
respectively second panel 210.2 includes cover layer 122 having a
low coefficient of friction, namely a low static coefficient of
friction. In the current example, coating 110 including first
anti-reflection coating 121.1 and cover layer 122 is applied onto
surface 212.1 of first panel 210.1. On outside 212.2 of second
panel 210.2, second anti-reflection coating 121.2 is also provided
in order to achieve very low reflectivity R.sub.vis in the entire
system. The substrate may alternatively also be a synthetic
substrate.
[0090] For application in display glasses of a smaller format, the
substrate may be .ltoreq.approximately 1 mm thick and is, for
example an ultra-thin substrate. Examples are the ultra-thin
glasses D263, B270 or Borofloat by SCHOTT AG.
[0091] If the devices are used for display glasses for larger
surfaces, for example surfaces larger than 1 meter squared
(m.sup.2), then substrates having a thickness of approximately 3 to
6 mm are used.
[0092] Through the secondary treatment in a low-/medium high vacuum
according to the inventive method as described in example 4 it is
possible to produce a substrate having a coefficient of friction in
the range of between approximately 0.01 to 0.12. This is
advantageous in regard to gliding of fingers or pens over the
surface, particularly when using such coated glasses in the area of
touchscreens or displays. Such layers having very low coefficients
of static friction also have poorer adherence of dirt on the
surface, so that contaminations, for example finger prints can be
wiped off easily with a dry cloth.
[0093] In special arrangements of the method, additional components
are to be mounted on the inventive described substrate, which are
used typically as display covers. Examples for this are
back-mounted support systems, for example of metal or front-mounted
optical docking systems. Standard procedure is to mount these
elements through adhesion. Since the described layers with low
coefficient of friction also have poor adhesion for bonded joints
it is advantageous in these cases to exclude the regions which are
to be glued together from the described coating process. The
relevant region can be masked for this purpose, for example using
an adhesion film, or also strippable lacquer in screen printing
technology. This masking has the effect that the layer formation
toward the surface of the substrate with overlying anti-reflection
coating is prevented and the gluing process onto partial regions is
implemented, which does not meet the requirement that the
coefficient of friction is very low. The masked regions are then,
for example, positioned in segments of the substrate which are not
visible in its application; this would for example be a housing
cover.
[0094] While this invention has been described with respect to at
least one embodiment, the present invention can be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains and which fall within the limits of
the appended claims.
* * * * *