U.S. patent application number 13/862679 was filed with the patent office on 2014-10-16 for hybrid single-side touch screen method.
The applicant listed for this patent is MITCHELL STEWART BURBERRY, Ronald Steven Cok. Invention is credited to MITCHELL STEWART BURBERRY, Ronald Steven Cok.
Application Number | 20140308435 13/862679 |
Document ID | / |
Family ID | 51686978 |
Filed Date | 2014-10-16 |
United States Patent
Application |
20140308435 |
Kind Code |
A1 |
BURBERRY; MITCHELL STEWART ;
et al. |
October 16, 2014 |
HYBRID SINGLE-SIDE TOUCH SCREEN METHOD
Abstract
A method of making a single-side touch-screen device includes
providing a substrate and forming a patterned arrangement of
micro-wires on the substrate. A patterned dielectric insulator is
formed over one or more middle portions of at least some of the
micro-wires forming insulated micro-wire portions and exposed
micro-wire portions. A plurality of patterned transparent
conductors is conformally coated in an array over at least a part
of the patterned dielectric insulator, at least a part of the
insulated micro-wire portions, and at least a part of the exposed
micro-wire portions. The at least a part of the exposed micro-wire
portions are electrically connected to at least a portion of the
patterned transparent conductors and form an array of electrically
connected horizontal electrodes and an array of electrically
connected vertical electrodes electrically isolated from the
horizontal electrodes.
Inventors: |
BURBERRY; MITCHELL STEWART;
(Webster, NY) ; Cok; Ronald Steven; (Rochester,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BURBERRY; MITCHELL STEWART
Cok; Ronald Steven |
Webster
Rochester |
NY
NY |
US
US |
|
|
Family ID: |
51686978 |
Appl. No.: |
13/862679 |
Filed: |
April 15, 2013 |
Current U.S.
Class: |
427/79 |
Current CPC
Class: |
G06F 3/0443 20190501;
G06F 3/0446 20190501; G06F 2203/04112 20130101; G06F 2203/04103
20130101; G06F 2203/04111 20130101 |
Class at
Publication: |
427/79 |
International
Class: |
G06F 3/044 20060101
G06F003/044 |
Claims
1. A method of making a single-side touch-screen device,
comprising: providing a substrate; forming a patterned arrangement
of micro-wires on the substrate; forming a patterned dielectric
insulator over one or more middle portions of at least some of the
micro-wires forming insulated micro-wire portions and exposed
micro-wire portions; conformally coating a plurality of patterned
transparent conductors in an array over at least a part of the
patterned dielectric insulator, at least a part of the insulated
micro-wire portions, and at least a part of the exposed micro-wire
portions; and thereby electrically connecting the at least a part
of the exposed micro-wire portions to at least a portion of the
patterned transparent conductors and forming an array of
electrically connected horizontal electrodes and an array of
electrically connected vertical electrodes electrically isolated
from the horizontal electrodes.
2. The method of claim 1, wherein forming a patterned arrangement
of micro-wires on the substrate includes: forming a curable layer
on the substrate; embossing a patterned arrangement of
micro-channels in the curable layer; curing the curable layer to
form the micro-channels; locating a curable material in the
micro-channels; and curing the curable material in the
micro-channels to form micro-wires in the micro-channels.
3. The method of claim 1, wherein forming a patterned arrangement
of micro-wires on the substrate includes: coating a flexographic
substrate with a conductive ink; and applying the conductive ink
coated on the flexographic substrate to the substrate to form the
micro-wires.
4. The method of claim 3, wherein the conductive ink is liquid and
further including drying the liquid ink to form the
micro-wires.
5. The method of claim 3, wherein the conductive ink is dry when
coated on the flexographic substrate.
6. The method of claim 1, wherein conformally coating the
transparent conductor includes atomic layer deposition of a
transparent conductive material.
7. The method of claim 6, further including patterning the
substrate with a coating of inhibitor material and conformally
coating the transparent conductor using atomic layer
deposition.
8. The method of claim 7, further including removing the inhibitor
material.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to commonly-assigned, co-pending U.S.
patent application Ser. No. ______ (Kodak Docket K001439), filed
concurrently herewith, entitled "Hybrid Single-Side Touch Screen"
by Mitchell Burberry et al, the disclosure of which is incorporated
herein.
FIELD OF THE INVENTION
[0002] The present invention relates to transparent electrodes
having micro-wires formed in micro-channels and in particular to
the micro-channel structure.
BACKGROUND OF THE INVENTION
[0003] Transparent conductors are widely used in the flat-panel
display industry to form electrodes that are used to electrically
switch light-emitting or light-transmitting properties of a display
pixel, for example in liquid crystal or organic light-emitting
diode displays. Transparent conductive electrodes are also used in
touch screens in conjunction with displays. In such applications,
the transparency and conductivity of the transparent electrodes are
important attributes. In general, it is desired that transparent
conductors have a high transparency (for example, greater than 90%
in the visible spectrum) and a low electrical resistivity (for
example, less than 10 ohms/square).
[0004] Transparent conductive metal oxides are well known in the
display and touch-screen industries and have a number of
disadvantages, including limited transparency and conductivity and
a tendency to crack under mechanical or environmental stress.
Typical prior-art conductive electrode materials include conductive
metal oxides such as indium tin oxide (ITO) or very thin layers of
metal, for example silver or aluminum or metal alloys including
silver or aluminum. These materials are coated, for example, by
sputtering or vapor deposition, and are patterned on display or
touch-screen substrates, such as glass. For example, the use of
transparent conductive oxides to form arrays of touch sensors on
one side of a substrate is taught in U.S. Patent Application
Publication 2011/0099805 entitled "Method of Fabricating Capacitive
Touch-Screen Panel".
[0005] Transparent conductive metal oxides are increasingly
expensive and relatively costly to deposit and pattern. Moreover,
the substrate materials are limited by the electrode material
deposition process (e.g. sputtering) and the current-carrying
capacity of such electrodes is limited, thereby limiting the amount
of power that is supplied to the pixel elements. Although thicker
layers of metal oxides or metals increase conductivity, they also
reduce the transparency of the electrodes.
[0006] Transparent electrodes including very fine patterns of
conductive elements, such as metal wires or conductive traces are
known. For example, U.S. Patent Publication No. 2011/0007011
teaches a capacitive touch screen with a mesh electrode, as do U.S.
Patent Publication No. 2010/0026664, U.S. Patent Publication No.
2010/0328248, and U.S. Pat. No. 8,179,381, which are hereby
incorporated in their entirety by reference. As disclosed in U.S.
Pat. No. 8,179,381, fine conductor patterns are made by one of
several processes, including laser-cured masking, inkjet printing,
gravure printing, micro-replication, and micro-contact printing. In
particular, micro-replication is used to form micro-conductors
formed in micro-replicated channels. The transparent micro-wire
electrodes include micro-wires between 0.5.mu. and 4.mu. wide and a
transparency of between approximately 86% and 96%.
[0007] Conductive micro-wires are formed in micro-channels embossed
in a substrate, for example as taught in CN102063951, which is
hereby incorporated by reference in its entirety. As discussed in
CN102063951, a pattern of micro-channels are formed in a substrate
using an embossing technique. Embossing methods are generally known
in the prior art and typically include coating a curable liquid,
such as a polymer, onto a rigid substrate. A pattern of
micro-channels is embossed (impressed) onto the polymer layer by a
master having an inverted pattern of structures formed on its
surface. The polymer is then cured. A conductive ink is coated over
the substrate and into the micro-channels, the excess conductive
ink between micro-channels is removed, for example by mechanical
buffing, patterned chemical electrolysis, or patterned chemical
corrosion. The conductive ink in the micro-channels is cured, for
example by heating. In an alternative method described in
CN102063951, a photosensitive layer, chemical plating, or
sputtering is used to pattern conductors, for example using
patterned radiation exposure or physical masks. Unwanted material
(e.g. photosensitive resist) is removed, followed by
electro-deposition of metallic ions in a bath.
[0008] Capacitive touch screen devices are constructed by locating
electrodes on either side of a dielectric layer. In another design,
electrodes are located on the same side of a substrate layer. U.S.
Pat. No. 8,274,486 discloses a touch screen assembly and method of
manufacturing thereof that includes a single layer of conductive
material. The conductive material is configured to include a
horizontal pattern and a vertical pattern of electrodes, with one
of the patterns having gaps between the electrodes, such that the
electrodes in the horizontal pattern do not come into direct
contact with electrodes in the vertical pattern. To provide a
connection between the electrodes separated by gaps in the
interrupted pattern, an insulating material is placed onto the gaps
over the uninterrupted pattern, and a printable and electrically
conductive connector is positioned over the insulating material and
functions to couple at least two electrodes together. In one
embodiment, the conductive connector includes carbon nanotubes.
[0009] There is a need, however, for further improvements in
conductivity, transparency, connectivity, and manufacturability for
micro-wire transparent electrodes and touch screens.
SUMMARY OF THE INVENTION
[0010] In accordance with the present invention, a method of making
a single-side touch-screen device comprises:
[0011] providing a substrate;
[0012] forming a patterned arrangement of micro-wires on the
substrate;
[0013] forming a patterned dielectric insulator over one or more
middle portions of at least some of the micro-wires forming
insulated micro-wire portions and exposed micro-wire portions;
[0014] conformally coating a plurality of patterned transparent
conductors in an array over at least a part of the patterned
dielectric insulator, at least a part of the insulated micro-wire
portions, and at least a part of the exposed micro-wire portions;
and
[0015] thereby electrically connecting the at least a part of the
exposed micro-wire portions to at least a portion of the patterned
transparent conductors and forming an array of electrically
connected horizontal electrodes and an array of electrically
connected vertical electrodes electrically isolated from the
horizontal electrodes.
[0016] The present invention provides an array of transparent touch
sensors arranged in arrays of electrically isolated horizontal and
vertical electrodes on one side of a substrate that have improved
conductivity and transparency and are more readily manufactured.
The transparent electrodes of the present invention are
particularly useful in capacitive touch screens and display
devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above and other features and advantages of the present
invention will become more apparent when taken in conjunction with
the following description and drawings wherein identical reference
numerals have been used to designate identical features that are
common to the figures, and wherein:
[0018] FIG. 1 is a plan view of an embodiment of the present
invention;
[0019] FIG. 2 is a plan view of a detail from FIG. 1 illustrating
an embodiment of the present invention;
[0020] FIG. 3 is a plan view of layer components illustrated in
FIGS. 1 and 2 according to an embodiment of the present
invention;
[0021] FIG. 4A is a plan view and corresponding cross section A of
an embodiment of the present invention;
[0022] FIG. 4B is a plan view and corresponding cross section B of
an embodiment of the present invention orthogonal to the cross
section of FIG. 4A;
[0023] FIG. 5 is a plan view and corresponding cross section C of
an alternative embodiment of the present invention having a narrow
micro-wire;
[0024] FIG. 6 is a plan view and corresponding cross section D of
another embodiment of the present invention having a printed
micro-wire;
[0025] FIG. 7 is a plan view of yet another embodiment of the
present invention having micro-wires and transparent conductors in
touch sensor areas;
[0026] FIG. 8 is a plan view of yet another embodiment of the
present invention having micro-wire touch sensors;
[0027] FIG. 9 is a flow diagram illustrating an embodiment of the
present invention;
[0028] FIG. 10 is a flow diagram illustrating patterning
micro-wires according to an embodiment of the present invention;
and
[0029] FIG. 11 is a flow diagram illustrating patterning
transparent conductors according to an embodiment of the present
invention.
[0030] The Figures are not drawn to scale since the variation in
size of various elements in the Figures is too great to permit
depiction to scale.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Referring to FIG. 1, the detail of FIG. 2, the exploded
illustration of FIG. 3, and the plan and cross sections of FIGS. 4A
and 4B, in an embodiment of the present invention a substrate 40
has a cured layer 10 formed on a substrate surface 41 of substrate
40. A patterned arrangement of micro-channels 60 are embossed in
cured layer 10. Each micro-channel 60 has a cured electrical
conductor forming a micro-wire 50 in the micro-channel 60. A
patterned dielectric insulator 20 is located over one or more
middle portions of at least some of micro-wires 50 forming
insulated micro-wire portions 51 and exposed micro-wire portions
52. As used herein, a middle portion of a micro-wire is a portion
of the micro-wire between and not including end portions of the
micro-wire.
[0032] A plurality of patterned transparent conductors 30 and
transparent conductor electrical connections 32 are conformally
coated in an array over at least a part of the patterned dielectric
insulator 20, at least a part of the insulated micro-wire portions
51, at least a part of the exposed micro-wire portions 52, and over
portions of a cured-layer surface of cured layer 10. The at least a
part of the exposed micro-wire portions 52 are electrically
connected to at least a portion of the patterned transparent
conductors 30. Transparent conductors 30 and micro-wires 50 form an
array of electrically connected horizontal electrodes 70 and an
array of electrically connected vertical electrodes 80 electrically
isolated from the horizontal electrodes 70. The designation of
horizontal and vertical are arbitrary and can be exchanged. As is
commonly known in the display and touch-screen arts, horizontal and
vertical refer to orthogonal directions over a substrate.
[0033] Horizontal electrodes 70 and vertical electrodes 80 can each
be connected to an electrical connection electrically controlled by
an external electrical circuit, for example an integrated circuit.
Horizontal and vertical electrodes, 70, 80 can be controlled to
enable a touch screen formed on the single, common substrate
surface 41 of substrate 40.
[0034] Referring specifically to FIGS. 1 and 2, diamond-shaped
electrically conductive touch sensors 90 are located in an
orthogonal array and are electrically connected to form horizontal
and vertical electrodes 70, 80. Each horizontal and vertical
electrode 70, 80 is electrically isolated from every other
horizontal and vertical electrode 70, 80. Each touch sensor 90 is
electrically continuous in a common plane (on cured-layer surface
12 in FIGS. 4A and 4B). Touch sensors 90 in vertical electrodes 80
are electrically connected by transparent conductor electrical
connections 32 as is seen in the leftmost vertical electrode in
FIG. 1. Touch sensors 90 in horizontal electrodes 70 are separated
by transparent conductor electrical connections 32 in vertical
electrodes 80 and are electrically connected by micro-channels 60
with micro-wires 50 (not shown). Patterned dielectric insulators 20
are located over the micro-channels 60 and under the transparent
conductor electrical connections 32 between touch sensors 90 in
horizontal and vertical electrodes 70, 80. Conformally coated
transparent conductors form patterned transparent conductor
electrical connections 32 between touch sensors 90 in vertical
electrodes 80 over patterned dielectric insulators 20 and, in an
embodiment, are formed in a common step with touch sensors 90.
Patterned dielectric insulators 20 electrically insulate
transparent conductor electrical connections 32 between touch
sensors 90 in vertical electrodes 80 from electrical connections
between touch sensors 90 in horizontal electrodes 70.
[0035] Specifically referring in more detail to FIG. 2, a two-by
two array of touch sensors 90 form portions of horizontal electrode
70 and vertical electrode 80. Micro-channel 60 with micro-wire 50
(not shown) extends between and electrically connects adjacent
touch sensors 90 in horizontal electrode 70. Dielectric insulator
20 is patterned over each juncture of horizontal and vertical
electrodes 70, 80 and over micro-channel 60 with micro-wire 50 (not
shown). Transparent conductor electrical connections 32 are
patterned over dielectric insulators 20 to electrically connect
touch sensors 90 in vertical electrodes 80 but are not electrically
connected to micro-wires 50 (not shown) in micro-channel 60. Thus
transparent conductor electrical connection 32 extends over the
edge of dielectric insulator 20 in the vertical direction to
electrically connect touch sensors 90 in vertical electrodes 80 but
does not extend over the edge of dielectric insulator 20 in the
horizontal direction and is therefore electrically isolated from
touch sensors 90 in horizontal electrodes 70 and micro-wires 50
(not shown) in micro-channels 60.
[0036] In an embodiment and as shown in FIGS. 1 and 2, touch
sensors 90 are formed from patterned transparent conductor 30.
Thus, touch sensors 90 and transparent conductor electrical
connection 32 are formed in a common step and are part of a layer
formed conformally over substrate 40 (not shown). The present
invention provides an advantage over the prior art in that
conformally coated transparent conductor touch sensors 90 and
transparent conductor electrical connections 32 are formed in a
common step and the conformal coating enables electrically
continuous coating over the edge of patterned dielectric insulator
20. Other methods for forming an electrical connector between
adjacent touch sensors 90 over a dielectric insulator 20 can be
prone to electrical discontinuities due to micro-wire breaks at the
edge of the transparent conductor 30, as is seen more clearly in
cross section and discussed further below.
[0037] Referring further to FIG. 3, each of the three layers in the
juncture between horizontal and vertical electrodes 70, 80 (not
shown) is separately illustrated. Micro-channel 60, located closest
to substrate surface 41 (not shown) extends beyond the horizontal
edges of dielectric insulator 20 to electrically connect
micro-wires 50 formed in micro-channels 60 to touch sensors 90 (not
shown) of horizontal electrodes 70 (not shown). Micro-wire 50 is
shown in the separate illustration of micro-channel 60. Transparent
conductor electrical connection 32 extends beyond the vertical
edges of dielectric insulator 20 to electrically connect touch
sensors 90 of vertical electrodes 80 but not beyond the horizontal
edges of dielectric insulator 20 to electrically isolate touch
sensors 90 of vertical electrodes 80 from micro-wires 50 and touch
sensors 90 of horizontal electrodes 70.
[0038] FIGS. 4A and 4B include orthogonal versions of the plan view
of FIG. 3 with corresponding and aligned cross sections taken along
cross section lines A and B, respectively. As shown in FIGS. 4A and
4B, cured-layer 10 having embossed micro-channels 60 with
micro-wires 50 is formed on substrate surface 41 of substrate 40.
Micro-wires 50 can, but do not necessarily, fill micro-channels 60.
Dielectric insulator 20 is formed over a portion of cured-layer
surface 12 and micro-wires 50 at the juncture between horizontal
and vertical electrodes 70, 80, (not shown) forming insulated
micro-wire portion 51 in the middle of micro-wire 50 and exposed
micro-wire portions 52 at the ends of the micro-wire 50.
Transparent conductor 30 is patterned over cured-layer surface 12
to form touch sensors 90 (not shown). Conformally coated
transparent conductors 30 forming touch sensors 90 in horizontal
electrodes 70 are electrically connected to corresponding
micro-wires 50. Transparent conductor electrical connections 32 are
patterned over dielectric insulator 20 to form corresponding
electrical connections between touch sensors 90 in vertical
electrodes 80. These electrical connections are facilitated by
conformal coating, since in practice the micro-wires 50 do not
necessarily extend to cured-layer surface 12 in embossed
micro-channel 60, as illustrated in FIGS. 4A and 4B or extend above
cured-layer surface 12 (as shown in FIG. 6 discussed below). The
electrical connection between touch sensors 90 in vertical
electrodes 80 and transparent conductor electrical connection 32 is
similarly facilitated by conformal coating since dielectric
insulator 20 can also form a vertical edge.
[0039] Micro-wire 50 illustrated in FIGS. 4A and 4B are relatively
long compared to the dielectric insulator 20 width. In some
embodiments, dielectric insulator 20 is deposited using inkjet
deposition of polymer material. Such deposition can have limited
resolution, for example 20 microns or greater. It is preferred that
micro-wires 50 that are for example typically opaque, are as small
as possible to reduce their visibility. Thus, as shown in the FIG.
5 plan view, micro-wire 50 is illustrated as much narrower than
dielectric insulator 20, for example as small as a few microns in
width, for example 4 microns or less. FIG. 5 cross section C
illustrates cured-layer 10 having embossed micro-channels 60 with
micro-wires 50 formed on substrate surface 41 of substrate 40.
Dielectric insulator 20 is formed over a portion of cured-layer
surface 12 and micro-wires 50 at the juncture between horizontal
and vertical electrodes 70, 80, forming insulated micro-wire
portion 51 in the middle of micro-wire 50 and exposed micro-wire
portions 52 at the ends of the micro-wire 50. Transparent conductor
30 is patterned over cured-layer surface 12 and dielectric
insulator 20 to form touch sensors 90 and transparent conductor
electrical connection 32 and corresponding electrical connections
between touch sensors 90 in horizontal electrodes 70 and vertical
electrodes 80 (not shown).
[0040] In an alternative embodiment illustrated in FIG. 6, printed
micro-wires 50 are formed on substrate surface 41 of substrate 40.
Dielectric insulator 20 is formed over portions of substrate
surface 41 and micro-wires 50 at the juncture between horizontal
and vertical electrodes 70, 80 (not shown), forming insulated
micro-wire portion 51 in the middle of micro-wire 50 and exposed
micro-wire portions 52 at the ends of the micro-wire 50.
Transparent conductor 30 is patterned over cured-layer surface 12
and dielectric insulator 20 to form touch sensors 90 (not shown)
and transparent conductor electrical connection 32 and
corresponding electrical connections between touch sensors 90 in
horizontal electrodes 70 and vertical electrodes 80 (not
shown).
[0041] In a further embodiment of the present invention, referring
to FIG. 7, micro-wires 55 extend along the length of horizontal
electrodes 70 and touch sensors 90 in horizontal electrodes 70
under dielectric insulator 20 in micro-channel 60. Micro-wires 56
extend along each touch sensor 90 in horizontal electrodes 80. Such
micro-wires can improve the conductivity of transparent conductor
30 in horizontal and vertical electrodes 70, 80 while maintaining
electrical isolation between horizontal and vertical electrodes 70,
80. More than one micro-wire 55 or 56 can be used in horizontal or
vertical electrodes 70, 80, respectively.
[0042] In another embodiment and as shown in FIG. 8, touch sensors
90 are formed from micro-wires 50. Micro-wires 50 are spaced apart
to form transparent electrodes, typically in a grid array of
electrically connected micro-wires 50 in one touch sensor 90,
although any useful pattern is included in the present invention.
Thus, touch sensors 90 and micro-wire 50 extending beneath
dielectric insulator 20 are formed in a common step and are part of
a single layer. In this embodiment, the function of transparent
conductor 30 in FIG. 2 is performed by the micro-wire grid array;
the other elements are the same and perform the same function.
Micro-wire 50 beneath dielectric insulator 20 electrically connects
touch sensors 90 (formed from a transparent micro-wire grid
electrode) in horizontal electrodes 70 and transparent conductor
electrical connection 32 electrically connects touch sensors 90
(also formed from a transparent micro-wire grid electrode) in
vertical electrodes 80. This embodiment of the present invention
provides an advantage over the prior art in that such micro-wires
50 can provide improved transparency and conductivity, as well as
enhanced manufacturability. Dielectric insulator 20 and transparent
conductor electrical connection 32 are formed as described above.
Transparent conductor electrical connection 32 electrically
connects to micro-wires 50 in the same way that transparent
conductor 30 electrically connects to micro-wires 50 in FIGS.
1-7.
[0043] Cured layer 10 is a layer of curable material that has been
cured. For example, cured layer 10 is formed of a curable material
coated or otherwise deposited on substrate surface 41 of substrate
40 to form a curable layer and then cured to form a cured layer 10.
The substrate-coated curable material is considered herein to be a
curable layer before it is cured and cured layer 10 after it is
cured. Similarly, a cured electrical conductor is an electrical
conductor formed by locating a curable material in micro-channel 60
and curing the curable material to form micro-wire 50 in
micro-channel 60.
[0044] As used herein, curing refers to changing the properties of
a material by processing the material in some fashion, for example
by heating, drying, irradiating the material, or exposing the
material to a chemical, energetic particles, gases, or liquids.
[0045] In an embodiment, cured layer 10 is a layer that is embossed
in a single step and cured in a single step. In another embodiment,
the embossing step and the curing step are different single steps.
For example, the curable layer is embossed in a first step using a
stamping method known in the art and cured in a second different
step, e.g. by heat or exposure to radiation to form cured layer 10.
In another embodiment, embossing and curing the curable layer is
done in a single common step. The curable layer is deposited as a
single layer in a single step using coating methods known in the
art, e.g. curtain coating. In an alternative embodiment, the
curable layer is deposited as multiple sub-layers using multi-layer
deposition methods known in the art, e.g. multi-layer slot coating,
repeated curtain coatings, or multi-layer extrusion coating. In yet
another embodiment, the curable layer includes multiple sub-layers
formed in different, separate steps, for example with a multi-layer
extrusion, curtain coating, or slot coating machine as is known in
the coating arts. Micro-channel 60 is embossed and cured in the
curable layer in a single step and micro-wires 50 are formed by
depositing a curable conductive ink in micro-channels 60 and curing
the curable conductive ink to form an electrically conductive
micro-wire 50.
[0046] Cured layer 10 useful in the present invention can include a
cured polymer material with cross-linking agents that are sensitive
to heat or radiation, for example infra-red, visible light, or
ultra-violet radiation. The polymer material is a curable material
applied in a liquid form that hardens when the cross-linking agents
are activated. When a molding device, such as an embossing stamp
having an inverse micro-channel structure is applied to liquid
curable material in the curable layer coated on substrate 40 and
the cross-linking agents in the curable material are activated, the
liquid curable material in the curable layer is hardened into cured
layer 10 having micro-channels 60. The liquid curable materials can
include a surfactant to assist in controlling coating on substrate
40. Materials, tools, and methods are known for embossing coated
liquid curable materials to form cured layers 10 having
conventional micro-channels.
[0047] Similarly, curable inks useful in the present invention are
known and can include conductive inks having electrically
conductive nano-particles, such as silver nano-particles. In an
embodiment, the electrically conductive nano-particles are metallic
or have an electrically conductive shell. The electrically
conductive nano-particles can be silver, can be a silver alloy, or
can include silver.
[0048] Curable inks provided in a liquid form are deposited or
located in micro-channels 60 and cured, for example by heating or
exposure to radiation such as infra-red, visible light, or
ultra-violet radiation. The curable ink hardens to form the cured
ink that makes up micro-wires 50. For example, a curable conductive
ink with conductive nano-particles are located within
micro-channels 60 and cured by heating or sintering to agglomerate
or weld the nano-particles together, thereby forming an
electrically conductive micro-wire 50. Materials, tools, and
methods are known for coating liquid curable inks to form
micro-wires 50 in conventional micro-channels.
[0049] Referring to FIG. 9 and to FIGS. 1-8, a method of making a
single-side touch-screen device according to an embodiment of the
present invention includes providing 100 a substrate 40. A
patterned arrangement of micro-wires 50 is formed 102 on or over
substrate 40. Dielectric insulator 20 is pattern-wise deposited 140
over at some portion of micro-wires 50 and transparent conductor 30
is pattern-wise deposited 150 on or over substrate 40 and
dielectric insulator 20.
[0050] Dielectric insulator 20 can be any of many known dielectric
materials included polymers or oxides and are deposited and
patterned 140 in any of a variety of known ways, including
pattern-wise inkjet deposition, sputter or coating through a mask
or blanket coated and patterned using known photo-lithographic
methods. Such known photo-lithographic technology can include a
photo-sensitive material that is optically patterned through a mask
to cure the photo-sensitive material and removal of uncured
material.
[0051] Micro-wires 50 are formed 102 in an embodiment by depositing
105 a polymer curable layer on first substrate surface 41 of
substrate 40. One or more micro-channels 60 are embossed 110 into
the curable layer. The curable layer is cured 115 to form cured
layer 10.
[0052] Curable ink is coated 120 over cured-layer surface 12 and
micro-channels 60 of cured layer 10 and excess curable ink removed
125 from cured-layer surface 12 so that curable ink is only located
in micro-channels 60. The curable ink is cured 130. The cured ink
forms electrically conductive micro-wires 50 in micro-channels
60.
[0053] According to various embodiments of the present invention,
the curable ink includes electrically conductive nano-particles and
curing step 130 sinters or agglomerates the electrically conductive
nano-particles to form micro-wires 50. In other embodiments, the
electrically conductive nano-particles are silver, a silver alloy,
include silver, or have an electrically conductive shell.
[0054] In another embodiment, coating 120 the curable ink includes
coating the curable ink in a liquid state and curing 130 the
curable ink includes curing the curable ink into a solid state.
[0055] Referring to FIG. 10 in an alternative embodiment,
micro-wires 50 are formed 102 by coating a flexographic substrate
106 having a raised pattern corresponding to a desired micro-wire
pattern with a conductive ink. The flexographic substrate is
brought into contact with substrate surface 41 to print 111 the
conductive ink onto substrate surface 41. In an optional step, the
conductive ink is dried 116. Flexographic substrates are known in
the flexographic printing arts.
[0056] In an embodiment, transparent conductor 30 and transparent
conductor electrical connection 32 are deposited by sputtering or
deposition and patterned either with masks or by photolithographic
processes. In another embodiment, atomic layer deposition methods
are used to form a transparent conductive layer, for example a
patterned aluminum zinc oxide layer using methods known in the art.
Patterning is accomplished by masking the deposition or by
photolithographic processes.
[0057] In an alternative embodiment, referring to FIG. 11, the
substrate is coated 107 with a patterned inhibitor and then atomic
layer deposition (ALD) is used to deposit 112 transparent
conductive material, for example aluminum zinc oxide. The patterned
inhibitor directs the growth of ALD-deposited material, for example
as disclosed in U.S. Pat. No. 8,273,654. By inhibiting the growth
where the deposition material is present, the deposition only
deposits in regions (selective areas) of the substrate where the
inhibitor is not present. The inhibitor prevents atomic layer
deposition, thereby forming a transparent conductor pattern that is
a reverse of the inhibitor-material pattern. Optionally, the
patterned inhibitor material is removed 117.
[0058] In an embodiment, a polymeric deposition inhibitor material
is cross-linked after applying the polymer onto the substrate,
before or during the patterning step. The deposition inhibitor
material is a compound or polymer that, after being applied, is
subsequently polymerized, cross linked, or polymerized and cross
linked. The deposition inhibitor material is a compound or polymer
that forms a self-assembled monolayer on the substrate. Polymers
are preferably addition polymers such as, for example, a
poly(perfluoroalkyl methacrylate); poly(perfluoroalkyl
methacrylate); poly(methyl methacrylate); poly(cyclohexyl
methacrylate); poly(benzyl methacrylate); poly(iso-butylene);
poly(9,9-dioctylfluorenyl-2,7-diyl); polystyrene; poly(vinyl
alcohol); poly(methyl methacrylate); poly(hexafluorobutyl
methacrylate), and copolymers thereof, wherein the alkyl has one to
six carbon atoms.
[0059] Cross linking is used to insolubilize a polymeric deposition
inhibitor material after application onto the surface of the
substrate. The cross linking can occur prior to patterning or can
occur during patterning in order to contribute to the patterning
step, for example, by employing cross linking initiated by, and
patterned by, actinic radiation, followed by removal of non-cross
linked polymer, for example, by solvent.
[0060] In an embodiment, the deposition inhibitor material is an
organosiloxane polymer. Organosiloxane polymers are defined to
include polymers, prepolymers, or macromonomers having at least 20
siloxane repeat units. Particularly preferred are deposition
inhibitor materials that, after application onto the substrate, and
any cross linking or intermolecular reaction, are insoluble. Such
organosiloxane polymers include random or block or cross linked
polymers or combinations thereof. Optionally, functional groups are
present on the organosiloxane polymer such as terminal groups (also
referred to as end caps). Cross linking groups or functional groups
or combinations of cross linking groups and functional groups can
also be present, for example, located on a side chain off a
siloxane backbone. Examples of organosiloxane polymers include
poly(alkylsiloxane), poly(arylsiloxane), poly(alkylarylsiloxane),
and poly(alkyl(aryl)siloxane), each optionally having functional
groups.
[0061] Functionalized poly(siloxanes) include epoxy-functionalized,
carboxyl-functionalized, polyether-functionalized,
phenol-functionalized, amino-functionalized, alkoxy-functionalized,
methacryl-functionalized, carbinol-functionalized,
hydroxy-functionalized, vinyl-functionalized,
acrylic-functionalized, silane-functionalized,
trifluoro-functionalized, or mercapto-functionalized
poly(organosiloxanes). Block copolymers can also be employed if
containing substantial siloxane repeat units. Such polymers can be
prepared as described in numerous patents and publications or are
commercially available from, for example, General Electric Company,
Schenectady, N.Y.; Dow Corning, Midland, Mich.; or Petrarch
Systems, Bristol, Pa.
[0062] The deposition inhibiting material layer includes one of a
self-assembled monolayer, a polymer, and a water-soluble polymer.
The self-assembled monolayer is performed by exposing the substrate
to a vapor, a liquid, or a liquid solution of a precursor material.
Precursor materials include silanes, phosphonates, thiols,
alcohols, amines, or ammonium salts. The polymer is soluble in any
convenient solvent and can have any useful molecular weight,
preferably in the range of 2,000 to 2,000,000. It can include a
single functional group, or can include a plurality of functional
groups. In the case of a plurality, the polymer can be a random,
periodic, or block polymer. For polymers with chiral centers the
polymer can be isotactic, syndiotactic, or atactic. The polymer can
have side chains and can be a graft copolymer. The polymer can be
linear or branched. The polymer can have low numbers of free acid
groups. Preferred polymers that a soluble in non polar solvents are
poly(methylmethcrylate), silicone polymers including
poly(dimethylsiloxane), poly(carbonates), poly(sulfones), and
poly(esters). Polymers with chemical modification are preferred,
including polymers modified with fluorine or fluorine containing
compounds. Polymers soluble in polar solvents such as water,
alcohols, or ketones are particularly preferred. Polymers can
include amide groups, such as poly(amide), poly(vinylpyrollidone),
and poly(2-ethyl-oxazoline). Polymers can include ether linkages,
such as poly(ethylene glycol). Polymers can include alcohol
functionalities, such as polyvinyl alcohol). Polymers can include
neutralized acid groups such as sodium polystyrene sulfonate) and
the sodium salt of poly(acrylic acid).
[0063] In some embodiments, the deposition inhibitor material is
chosen specifically for the material to be deposited. The
deposition inhibitor material has a given inhibition power. The
inhibition power is defined as the layer thickness at or below
which the deposition inhibitor material is effective. Preferably,
the deposition inhibitor material, during use, exhibits an
inhibition power of at least 50 .ANG., more preferably at least 100
.ANG., most preferably at least 300 .ANG.. The deposition of the
deposition inhibitor material is in a patterned manner, such as
using inkjet, flexography, gravure printing, micro-contact
printing, offset lithography, patch coating, screen printing, or
transfer from a donor sheet. In alternative embodiments, a uniform
layer of the deposition inhibitor material is deposited and then
patterned form a patterned layer of the deposition inhibitor
material. Preprocessing treatments for patterning the inhibitor
include patterning of substrate prior to inhibitor application to
modify the hydrophobicity, electric charge, absorption, or
roughness of the substrate. Post processing treatments include
light exposure, light exposure and subsequent liquid based
development, and ablation.
[0064] Providing the patterned deposition inhibiting material layer
on the substrate includes using at least one of an inkjet printing
process, a flexographic printing process, a gravure printing
process, and a photolithographic printing process. The active
inhibiting material is suspended or dissolved in a solvent or
vehicle. The material can include surfactants, stabilizers, or
viscosity modifiers. The printed material is dried using natural
convection, forced convection, or radiant heat. The material is
treated to change its morphology or chemical composition. A
preferred chemical composition change is to crosslink the material.
The change in morphology or chemical composition is accomplished by
exposure to a vapor phase or liquid phase reactant, or treatment
with heat or light. Preferred processes include the cross-linking
of material with UV light.
[0065] According to various embodiments of the present invention,
substrate 40 is any material having a first surface 41 on which a
cured layer 10 is formed. Substrate 40 is a rigid or a flexible
substrate made of, for example, a glass, metal, plastic, or polymer
material, can be transparent, and can have opposing substantially
parallel and extensive surfaces. Substrates 40 can include a
dielectric material useful for capacitive touch screens and can
have a wide variety of thicknesses, for example 10 microns, 50
microns, 100 microns, 1 mm, or more. In various embodiments of the
present invention, substrates 40 are provided as a separate
structure or are coated on another underlying substrate, for
example by coating a polymer substrate layer on an underlying glass
substrate.
[0066] Substrate 40 is an element of other devices, for example the
cover or substrate of a display or a substrate, cover, or
dielectric layer of a touch screen. According to embodiments of the
present invention, micro-wires 50 extend across at least a portion
of substrate 40 in a direction parallel to substrate surface 41 of
substrate 40. In an embodiment, a substrate 40 of the present
invention is large enough for a user to directly interact
therewith, for example using an implement such as a stylus or using
a finger or hand. Methods are known in the art for providing
suitable surfaces on which to coat a single curable layer. In a
useful embodiment, substrate 40 is substantially transparent, for
example having a transparency of greater than 90%, 80% 70% or 50%
in the visible range of electromagnetic radiation.
[0067] Electrically conductive micro-wires 50 and methods of the
present invention are useful for making electrical conductors and
busses for transparent micro-wire electrodes and electrical
conductors in general, for example as used in electrical busses. A
variety of micro-wire patterns are used and the present invention
is not limited to any one pattern. Micro-wires 50 can be spaced
apart, form separate electrical conductors, or intersect to form a
mesh electrical conductor on, in, or above substrate 40.
Micro-channels 60 can be identical or have different sizes, aspect
ratios, or shapes. Similarly, micro-wires 50 can be identical or
have different sizes, aspect ratios, or shapes. Micro-wires 50 can
be straight or curved.
[0068] A micro-channel 60 is a groove, trench, or channel formed on
or in substrate 40 extending from cured-layer surface 12 toward
substrate surface 41 of substrate 40 and having a cross-sectional
width for example less than 20 microns, 10 microns, 5 microns, 4
microns, 3 microns, 2 microns, 1 micron, or 0.5 microns, or less.
In an embodiment, cross-sectional depth of micro-channel 60 is
comparable to its width. Micro-channels 60 can have a rectangular
cross section, as shown. Other cross-sectional shapes, for example
trapezoids, are known and are included in the present invention.
The width or depth of a layer is measured in cross section.
[0069] In various embodiments, cured inks can include metal
particles, for example nano-particles. The metal particles are
sintered to form a metallic electrical conductor. The metal
nano-particles are silver or a silver alloy or other metals, such
as tin, tantalum, titanium, gold, copper, or aluminum, or alloys
thereof. Cured inks can include light-absorbing materials such as
carbon black, a dye, or a pigment.
[0070] In an embodiment, a curable ink can include conductive
nano-particles in a liquid carrier (for example an aqueous solution
including surfactants that reduce flocculation of metal particles,
humectants, thickeners, adhesives or other active chemicals). The
liquid carrier is located in micro-channels 60 and heated or dried
to remove liquid carrier or treated with hydrochloric acid, leaving
a porous assemblage of conductive particles that can be
agglomerated or sintered to form a porous electrical conductor in a
layer. Thus, in an embodiment, curable inks are processed to change
their material compositions, for example conductive particles in a
liquid carrier are not electrically conductive but after processing
form an assemblage that is electrically conductive.
[0071] Once deposited, the conductive inks are cured, for example
by heating. The curing process drives out the liquid carrier and
sinters the metal particles to form a metallic electrical
conductor. Conductive inks are known in the art and are
commercially available. In any of these cases, conductive inks or
other conducting materials are conductive after they are cured and
any needed processing completed. Deposited materials are not
necessarily electrically conductive before patterning or before
curing. As used herein, a conductive ink is a material that is
electrically conductive after any final processing is completed and
the conductive ink is not necessarily conductive at any other point
in micro-wire 50 formation process.
[0072] In various embodiments of the present invention,
micro-channel 60 or micro-wire 50 has a width less than or equal to
10 microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1
micron. In an example and non-limiting embodiment of the present
invention, each micro-wire 50 is from 10 to 15 microns wide, from 5
to 10 microns wide, or from 5 microns to one micron wide. In some
embodiments, micro-wire 50 can fill micro-channel 60; in other
embodiments micro-wire 50 does not fill micro-channel 60. In an
embodiment, micro-wire 50 is solid; in another embodiment
micro-wire 50 is porous.
[0073] Micro-wires 50 can be metal, for example silver, gold,
aluminum, nickel, tungsten, titanium, tin, or copper or various
metal alloys including, for example silver, gold, aluminum, nickel,
tungsten, titanium, tin, or copper. Micro-wires 50 can include a
thin metal layer composed of highly conductive metals such as gold,
silver, copper, or aluminum. Other conductive metals or materials
can be used. Alternatively, micro-wires 50 can include cured or
sintered metal particles such as nickel, tungsten, silver, gold,
titanium, or tin or alloys such as nickel, tungsten, silver, gold,
titanium, or tin. Conductive inks are used to form micro-wires 50
with pattern-wise deposition or pattern-wise formation followed by
curing steps. Other materials or methods for forming micro-wires
50, such as curable ink powders including metallic nano-particles,
are employed and are included in the present invention.
[0074] Electrically conductive micro-wires 50 of the present
invention can be operated by electrically connecting micro-wires 50
through connection pads and electrical connectors to electrical
circuits that provide electrical current to micro-wires 50 and can
control the electrical behavior of micro-wires 50. Electrically
conductive micro-wires 50 of the present invention are useful, for
example in touch screens such as projected-capacitive touch screens
that use transparent micro-wire electrodes and in displays.
Electrically conductive micro-wires 50 can be located in areas
other than display areas, for example in the perimeter of the
display area of a touch screen, where the display area is the area
through which a user views a display.
[0075] A single-side touch-screen device has been constructed. A
glass substrate was coated with a transparent, UV sensitive
photo-resist SU8-2010 (available from MicroChem) to form a curable
layer approximately 10 microns thick. Micro-channels 60 were formed
in the curable layer and the structure cured to form a cured layer
10 having micro-channels 60. A curable conductive ink was coated
over the cured layer 10 and in micro-channels 60, excess material
removed from the cured layer 10, and the curable conductive ink in
the micro-channels 60 cured to form patterned micro-wires 50 in the
micro-channels 60. A photo-resist was coated and patterned over the
cured layer 10 to form patterned dielectric insulators 20 forming
insulated micro-wire portions 51 having a thickness of
approximately 0.5 microns. A layer of aluminum zinc oxide was
coated using atomic layer deposition over cured layer 10,
dielectric insulators 20, and exposed micro-wire portions 52. The
layer of aluminum zinc oxide was patterned to form the structure
illustrated in FIGS. 1-3, 4A, and 4B.
[0076] Methods and devices for forming and providing substrates and
coating substrates are known in the photo-lithographic arts.
Likewise, tools for laying out electrodes, conductive traces, and
connectors are known in the electronics industry as are methods for
manufacturing such electronic system elements. Hardware controllers
for controlling touch screens and displays and software for
managing display and touch screen systems are well known. These
tools and methods can be usefully employed to design, implement,
construct, and operate the present invention. Methods, tools, and
devices for operating capacitive touch screens are used with the
present invention.
[0077] The present invention is useful in a wide variety of
electronic devices. Such devices can include, for example,
photovoltaic devices, OLED displays and lighting, LCD displays,
plasma displays, inorganic LED displays and lighting,
electrophoretic displays, electrowetting displays, dimming mirrors,
smart windows, transparent radio antennae, transparent heaters and
other touch-screen devices such as capacitive touch screen
devices.
[0078] The invention has been described in detail with particular
reference to certain embodiments thereof, but it will be understood
that variations and modifications can be effected within the spirit
and scope of the invention.
PARTS LIST
[0079] A cross section [0080] B cross section [0081] C cross
section [0082] D cross section [0083] 10 cured layer [0084] 12
cured-layer surface [0085] 20 dielectric insulator [0086] 30
transparent conductor [0087] 32 transparent conductor electrical
connection [0088] 40 substrate [0089] 41 substrate surface. [0090]
50 micro-wire [0091] 51 insulated micro-wire portion/middle portion
[0092] 52 exposed micro-wire portion [0093] 55 micro-wire [0094] 56
micro-wire [0095] 60 micro-channel [0096] 70 horizontal electrode
[0097] 80 vertical electrode [0098] 90 touch sensor [0099] 100
provide substrate step [0100] 102 form micro-wires step [0101] 105
deposit curable layer step [0102] 106 coat flexographic substrate
with conductive ink step [0103] 107 pattern substrate with
inhibitor step [0104] 110 emboss micro-channels step [0105] 111
print substrate with coated flexographic ink step [0106] 112
deposit atomic layer of transparent conductor step [0107] 115 cure
curable layer step [0108] 116 optional dry ink step [0109] 117
optional remove patterned inhibitor step [0110] 120 coat curable
ink step [0111] 125 remove excess conductive ink step [0112] 130
cure conductive ink step [0113] 140 deposit patterned dielectric
step [0114] 150 deposit patterned transparent conductor step
* * * * *