U.S. patent application number 14/191484 was filed with the patent office on 2015-08-27 for making micro-wire electrode structure with single-layer dummy micro-wires.
The applicant listed for this patent is Ronald Steven Cok. Invention is credited to Ronald Steven Cok.
Application Number | 20150242025 14/191484 |
Document ID | / |
Family ID | 51626589 |
Filed Date | 2015-08-27 |
United States Patent
Application |
20150242025 |
Kind Code |
A1 |
Cok; Ronald Steven |
August 27, 2015 |
MAKING MICRO-WIRE ELECTRODE STRUCTURE WITH SINGLE-LAYER DUMMY
MICRO-WIRES
Abstract
A method of making a micro-wire electrode structure includes
providing a substrate having a surface. A plurality of first
micro-wire electrodes spatially separated by first electrode gaps
is located in a first layer in relation to the surface, each first
micro-wire electrode including a plurality of electrically
connected first micro-wires. A plurality of electrically isolated
second micro-wire electrodes in a second layer is located in
relation to the surface, the second layer at least partially
different from the first layer and each second micro-wire electrode
including a plurality of electrically connected second micro-wires.
A plurality of first gap micro-wires is located in each first
electrode gap, at least some of the first gap micro-wires located
in a gap layer different from the first layer, the first gap
micro-wires electrically isolated from the first micro-wires.
Inventors: |
Cok; Ronald Steven;
(Rochester, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cok; Ronald Steven |
Rochester |
NY |
US |
|
|
Family ID: |
51626589 |
Appl. No.: |
14/191484 |
Filed: |
February 27, 2014 |
Current U.S.
Class: |
29/622 |
Current CPC
Class: |
Y10T 29/49117 20150115;
G06F 3/042 20130101; G06F 3/0446 20190501; Y10T 29/49105 20150115;
H05K 1/0216 20130101; H05K 2201/10204 20130101; G06F 3/0412
20130101; G06F 3/046 20130101; G06F 2203/04112 20130101; G06F 1/16
20130101; G06F 3/047 20130101; G06F 2203/04107 20130101; G06F
3/04164 20190501; G06F 3/0445 20190501; H05K 1/0296 20130101; G06F
2203/04103 20130101; G06F 2203/04111 20130101 |
International
Class: |
G06F 3/047 20060101
G06F003/047; G06F 3/044 20060101 G06F003/044 |
Claims
1. A method of making a micro-wire electrode structure, comprising:
providing a substrate having a surface; locating a plurality of
first micro-wire electrodes spatially separated by first electrode
gaps in a first layer in relation to the surface, each first
micro-wire electrode including a plurality of electrically
connected first micro-wires; locating a plurality of electrically
isolated second micro-wire electrodes in a second layer in relation
to the surface, the second layer at least partially different from
the first layer and each second micro-wire electrode including a
plurality of electrically connected second micro-wires; and
locating a plurality of first gap micro-wires in each first
electrode gap, at least some of the first gap micro-wires located
in a gap layer different from the first layer, the first gap
micro-wires electrically isolated from the first micro-wires.
2. The method of claim 1, further including locating an unpatterned
conductive layer in electrical contact with the first micro-wires
of the first micro-wire electrodes.
3. The method of claim 1, further including locating at least some
of the first gap micro-wires and locating at least some of the
second micro-wires in the second layer in a common step so that the
at least some of the first gap micro-wires are within the second
micro-wire electrodes and are electrically connected to the second
micro-wires.
4. The method of claim 1, further including spatially separating
the second micro-wire electrodes by second electrode gaps and
locating a plurality of second gap micro-wires in each second
electrode gap, the second gap micro-wires electrically isolated
from the second micro-wires.
5. The method of claim 4, further including locating at least some
of the second gap micro-wires and at least some of the first gap
micro-wires in a common layer parallel to the surface in a common
step.
6. The method of claim 5, further including locating at least some
of the second gap micro-wires and locating at least some of the
first gap micro-wires in a common step in the first layer and the
first layer is the common layer.
7. The method of claim 6, further including locating the second
micro-wires and locating at least some of the first gap micro-wires
within the second micro-wire electrodes and electrically connected
to the second micro-wires in a common step.
8. The method of claim 6, further including locating the second gap
micro-wires and locating at least some of the first gap micro-wires
within the second electrode gap and electrically connected to the
second gap micro-wires in a common step.
9. The method of claim 1, further including locating the first
layer between the second layer and the surface and before the
second layer is located.
10. The method of claim 9, further including providing an
unpatterned conductive layer in electrical contact with the first
micro-wires of the first micro-wire electrodes before the second
layer is located.
11. The method of claim 9, further including driving the first
micro-wire electrodes with a signal and sensing the second
micro-wire electrodes to provide a signal for a capacitive touch
screen.
12. The method of claim 1, further including locating the second
layer between the first layer and the surface before the first
layer is located.
13. The method of claim 12, further including driving the second
micro-wire electrodes with a signal and sensing the first
micro-wire electrodes to provide a signal for a capacitive touch
screen.
14. The method of claim 1, further including providing a display
substrate or a display cover having the surface or affixing the
substrate to a display and wherein the display is the source of
electromagnetic radiation.
15. The method of claim 1, further including locating the first
micro-wire electrodes extending in a first direction parallel to
the surface and locating the second micro-wire electrodes extending
in a second direction parallel to the surface.
16. The method of claim 15, wherein the first direction is
orthogonal to the second direction.
17. The method of claim 15, further including forming a first
pattern with the first micro-wires, and forming a second pattern
similar to the first pattern with the second micro-wires.
18. The method of claim 17, wherein the first pattern is spatially
offset from the second pattern in a direction parallel to the
surface by a phase difference of 180 degrees.
19. The method of claim 1, further including locating the first
micro-wire electrodes so that the first micro-wire electrodes are
electrically isolated.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to commonly-assigned co-pending U.S.
patent application Ser. No. ______ (Attorney Docket No.
K001713USO1RLO) filed concurrently herewith, entitled Micro-Wire
Electrode Structure with Single-Layer Dummy Micro-Wires, by Cok,
the disclosure of which is incorporated herein.
[0002] Reference is made to commonly-assigned co-pending U.S.
patent application Ser. No. 14/032,213, filed Sep. 20, 2013
entitled Micro-Wire Touch Screen with Unpatterned Conductive Layer,
by Burberry et al.; and to commonly-assigned co-pending U.S. patent
application Ser. No. 14/1677,134, filed Jan. 29, 2014. entitled
Micro-Wire Electrodes with Equi-Potential Dummy Micro-Wires, by
Cok; the disclosures of which are incorporated herein.
FIELD OF THE INVENTION
[0003] The present invention relates to touch screens having
micro-wire electrodes and an unpatterned transparent conductor
layer.
BACKGROUND OF THE INVENTION
[0004] 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).
[0005] 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 senses on one
side of a substrate is taught in U.S. Patent Application
Publication No. 2011/0099805 entitled "Method of Fabricating
Capacitive Touch-Screen Panel".
[0006] 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 (such as sputtering) and the current-carrying
capacity of such electrodes is limited, thereby limiting the amount
of power that is supplied to the pixel elements and the size of
touch screens that employ such electrodes. Although thicker layers
of metal oxides or metals increase conductivity, they also reduce
the transparency of the electrodes.
[0007] Apparently transparent electrodes including very fine
patterns of conductive elements, such as metal wires or conductive
traces are known. For example, U.S. Patent Application Publication
No. 2011/0007011 teaches a capacitive touch screen with a mesh
electrode, as do U.S. Patent Application Publication No.
2010/0026664, U.S. Patent Application 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 apparently transparent micro-wire
electrodes include micro-wires between 0.5.mu. and 4.mu. wide and a
transparency of between approximately 86% and 96%.
[0008] 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 or imprinted) 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 (such as photosensitive resist) is removed, followed by
electro-deposition of metallic ions in a bath.
[0009] Mutual capacitive touch screen devices are constructed by
locating drive electrodes near sense electrodes to form an electric
field. In one prior-art design, the drive and sense electrodes are
located on a common substrate with bridge electrical connections to
prevent electrical shorts between the drive and sense electrodes
where the drive electrodes cross over or under the sense
electrodes. In another prior-art design, the drive and sense
electrodes are located on either side of a dielectric layer.
Referring to FIG. 11, a prior-art display and touch-screen
apparatus 100 includes a display 110 with a corresponding touch
screen 120 mounted with the display 110 so that information
displayed on the display 110 can be viewed through the touch screen
120. Graphic elements displayed on the display 110 are selected,
indicated, or manipulated by touching a corresponding location on
the touch screen 120. The touch screen 120 includes a first
transparent substrate 122 with transparent first electrodes 130
extending in the x dimension on the first transparent substrate 122
and a second transparent substrate 126 with transparent second
electrodes 132 extending in the y dimension facing the x-dimension
transparent first electrodes 130 on the second transparent
substrate 126. A dielectric layer 124 is located between the first
and second transparent substrates 122, 126 and transparent first
and second electrodes 130, 132. Touch pad areas 128 are formed by
the overlap of the transparent first electrodes 130 with the
transparent second electrodes 132. When a voltage is applied across
the transparent first and second electrodes 130, 132, electric
fields are formed between them that are measurable to detect
changes in capacitance due to the presence of a touch element, such
as a finger or stylus.
[0010] A display controller 142 connected through electrical bus
connections 136 controls the display 110 in cooperation with a
touch-screen controller 140. The touch-screen controller 140 is
connected through electrical bus connections 136 and wires 134 and
controls the touch screen 120. The touch-screen controller 140
detects touches on the touch screen 120 by sequentially
electrically energizing and testing the apparently transparent
x-dimension first and y-dimension second electrodes 130, 132.
[0011] Referring to FIG. 12 as well as FIG. 11, in another
prior-art embodiment, the rectangular transparent first electrodes
130 separated by first electrode gaps 60 and transparent second
electrodes 132 separated by second electrode gaps 62 include
micro-wires 150 and are arranged orthogonally in a micro-pattern
156 on transparent first and second substrates 122, 126 with
intervening dielectric layer 124, forming touch screen 120 which,
in combination with the display 110 forms the touch screen 120 and
display and touch screen apparatus 100.
[0012] As is known in the prior art, electromagnetic interference
from the display 110 can interfere with the operation of the
touch-screen 120. This problem is mitigated by providing a ground
plane between the touch screen 120 and display 110. However, such a
structure undesirably increases the thickness and decreases the
transparency of the display and touch screen apparatus 100.
[0013] Alternatively, it has been recognized that shielding is
achieved by controlling the relative width of the drive and sense
electrodes. For example U.S. Pat. No. 7,920,129 discloses a
multi-touch capacitive touch-sense panel created using a substrate
with column and row traces formed on either side of the substrate.
To shield the column (sense) traces from the effects of capacitive
coupling from a modulated V.sub.com layer in an adjacent liquid
crystal display (LCD) or any source of capacitive coupling, the row
traces were widened to shield the column traces, and the row
(drive) traces were placed closer to the LCD. In particular, the
rows are widened so that there is spacing of about 30 microns
between adjacent row traces. In this manner, the row traces can
serve the dual functions of driving the touch sense panel, and also
the function of shielding the more sensitive column (sense) traces
from the effects of capacitive coupling.
[0014] Shielding has also been achieved by using metal micro-wire
sense electrodes in combination with transparent conductive drive
electrodes. For example U.S. Pat. No. 8,279,187 discloses a
multi-layer touch panel having an upper electrode layer having a
plurality of composite electrodes including a plurality of metal or
metal alloy micro-wire conductors with a cross-sectional dimension
of less than 10 microns, a lower electrode layer having a plurality
of (patterned) indium oxide-based electrodes, the upper electrodes
and lower electrodes defining an electrode matrix having nodes
where the upper and lower electrodes cross over. The upper
electrode layer is disposed between the first layer and the lower
electrode layer and a dielectric layer is disposed between the
upper electrode layer and the lower electrode layer. As noted
above, it is difficult, expensive, or impossible to meet
conductivity requirements for larger touch-screens using patterned
indium tin oxide electrodes.
[0015] In general, touch screens are intended to be invisible to a
user. It is important, therefore, that any conductive structures in
a touch screen be visually imperceptible. In prior-art designs,
apparently transparent conductive electrodes made of transparent
conductive oxides reduce electrode visibility. Nonetheless, such
electrodes do absorb some light, having a transparency for example
of 88% in the visible range and a slightly yellow appearance. Thus,
electrode structures in a touch screen having transparent
conductive oxides are visible to perceptive users. In particular,
regular first electrode gaps 60 between transparent first
electrodes 130 and second electrode gaps 62 between transparent
second electrodes 132 are visible as areas with increased
transparency.
[0016] Referring to FIG. 13, to reduce the visibility of gaps
between electrodes in a touch screen, dummy conductive structures
are provided in the first electrode gap 60. These dummy structures
typically include conductive materials and structures similar to
those found in the electrodes but are not electrically connected to
the electrodes. Thus, the dummy structures provide optical
uniformity in the touch screen by providing structures with an
appearance similar to the electrodes but without any electrical
function. Micro-wire breaks 64 or other conductive element breaks
between the dummy structures and the electrodes to maintain
electrical isolation between the dummy structures and the
electrodes are typically so small (for example, a few microns) that
the micro-wire breaks 64 are imperceptible to viewers. As shown in
FIG. 13, a plurality of rectangular, spatially separated
transparent first electrodes 130 connected to wires 134 in an
electrical bus connection 136 are arranged in an array on a first
transparent substrate 122. Each transparent first electrode 130
includes a plurality of electrically connected micro-wires 150.
Dummy micro-wires 152 located in first electrode gaps 60 between
the transparent first electrodes 130 are arranged in a similar way
so that the dummy micro-wires 152 located in the first electrode
gaps 60 between the transparent first electrodes 130 appear similar
to the micro-wires in transparent first electrodes 130.
[0017] U.S. Patent Application Publication No. 2011/0248953
entitled "Touch Screen Panel" describes conductive dummy patterns
between adjacent sensing cells in a touch screen panel. U.S. Patent
Application Publication No. 2011/0289771 entitled "Method for
Producing Conductive Sheet and Method for Producing Touch Panel"
describes unconnected dummy patterns formed near each side of a
sensing region. U.S. Pat. No. 7,663,607 entitled "Multi-Point Touch
Screen" describes dummy features disposed between driving lines and
sensing lines to optically improve the visual appearance of the
touch screen. The dummy features provide the touch screen with a
more uniform appearance and are electrically isolated and
positioned in the gaps between each of the lines. Although they can
be patterned separately, the dummy features are typically patterned
along with the lines and formed with the same conductive materials.
The dummy features still produce some gaps but the gaps are much
smaller than the gaps found between the lines.
SUMMARY OF THE INVENTION
[0018] There remains a need for further improvements in the
structure of a display and touch-screen apparatus that improves
sensitivity and efficiency, reduces susceptibility to
electromagnetic interference, and improves optical uniformity.
[0019] In accordance with the present invention, a method of making
a micro-wire electrode structure comprises:
[0020] providing a substrate having a surface;
[0021] locating a plurality of first micro-wire electrodes
spatially separated by first electrode gaps in a first layer in
relation to the surface, each first micro-wire electrode including
a plurality of electrically connected first micro-wires;
[0022] locating a plurality of electrically isolated second
micro-wire electrodes in a second layer in relation to the surface,
the second layer at least partially different from the first layer
and each second micro-wire electrode including a plurality of
electrically connected second micro-wires; and
[0023] locating a plurality of first gap micro-wires in each first
electrode gap, at least some of the first gap micro-wires located
in a gap layer different from the first layer, the first gap
micro-wires electrically isolated from the first micro-wires.
[0024] The present invention provides a micro-wire electrode
structure useful in capacitive touch screens having improved
sensitivity, efficiency, consistency, optical uniformity, and
reduced susceptibility to electromagnetic interference. By locating
dummy micro-wires from one layer in another layer, electrode
electrical performance is improved and optical uniformity
maintained or improved.
[0025] The presence of an unpatterned conductive layer electrically
connected to first electrodes and first micro-wires provides
electromagnetic shielding to the first and second electrodes,
thereby reducing electromagnetic interference. The integrated
unpatterned conductive layer therefore reduces device thickness by
reducing the number of insulating layers. This has the additional
benefit of reducing conductive layer thickness and improving
transparency in comparison to a conventional shielding system.
[0026] The presence of the unpatterned conductive layer also
increases capacitance between the first and second electrodes,
thereby reducing the voltage needed to sense changes in the
capacitive field, for example due to touches, thereby improving
efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] 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:
[0028] FIGS. 1A, 1B, and 1C are plan views of different layers of a
micro-wire electrode structure according to an embodiment of the
present invention;
[0029] FIG. 1D is a perspective combining the layers of FIGS. 1A,
1B, and 1C;
[0030] FIGS. 2A, 2B and 2C are plan views of the same layer of a
micro-wire electrode structure with different micro-wire markings
according to another embodiment of the present invention;
[0031] FIG. 2C is a plan view of a layer of a micro-wire electrode
structure according to another embodiment of the present
invention;
[0032] FIG. 2D is a perspective combining the layers of FIGS. 2A,
2B, and 2C;
[0033] FIG. 3A is a plan view of a layer of a micro-wire electrode
structure according to yet another embodiment of the present
invention;
[0034] FIGS. 3B and 3C are plan views of the same layers of a
micro-wire electrode structure with different micro-wire markings
according to yet another embodiment of the present invention;
[0035] FIG. 3D is a plan view of a layer of a micro-wire electrode
structure according to yet another embodiment of the present
invention;
[0036] FIGS. 3E and 3F are perspectives combining the layers of
FIGS. 3A, 3B, 3C and 3D, in different embodiments of the present
invention;
[0037] FIGS. 4A and 4B are plan views of the same layer of a
micro-wire electrode structure with different micro-wire markings
according to a further embodiment of the present invention;
[0038] FIGS. 4C and 4D are plan views of different layers of a
micro-wire electrode structure according to a further embodiment of
the present invention;
[0039] FIGS. 5 and 6 are cross sectional views of different
embodiments of the present invention;
[0040] FIGS. 7-10 are flow diagrams illustrating various methods of
various embodiments of the present invention;
[0041] FIG. 11 is a prior-art perspective of a capacitive touch
screen;
[0042] FIG. 12 is a plan view of two prior-art overlapping
micro-wire electrodes useful in understanding the present
invention;
[0043] FIG. 13 is a schematic illustrating prior-art micro-wire
electrodes and dummy micro-wires useful in understanding the
present invention; and
[0044] FIG. 14 is a cross sectional view of yet another embodiment
of the present invention.
[0045] 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
[0046] The present invention provides a micro-wire electrode
structure useful in forming capacitive touch-screen devices and in
combination with a display. The micro-wire electrode structure
improves electrode conductivity, optical uniformity, reduces the
effects of electromagnetic interference, and improves
touch-response sensitivity, efficiency, and consistency over the
extent of the touch screen. The micro-wire electrode structure of
the present invention is also useful in other applications
requiring overlapping micro-wire electrodes and is not limited to
applications of touch-screen devices. According to embodiments of
the present invention, dummy wires provided for optical uniformity
found in layers of conventional prior-art designs are instead used
in different layers to improve electrode conductivity or resistance
to electromagnetic interference.
[0047] FIGS. 1A, 1B, and 1C are plan views of layers forming a
multi-layer structure. The layers are shown in combination in the
perspective of FIG. 1D. Referring to FIG. 1D, a micro-wire
electrode structure 5 includes a substrate 10 with first and second
opposing sides, one of which provides a surface 12. In various
embodiments, the substrate 10 is an element of a display 110, for
example a cover or substrate of the display 110, or is affixed to
the display 110. In an embodiment, the display 110 is a source of
electromagnetic radiation located on or adjacent to the second
opposing side.
[0048] As shown in FIGS. 1A and 1D, a plurality of electrically
isolated first micro-wire electrodes 22 spatially separated by
first electrode gaps 60 is located in a first layer 20 in relation
to the surface 12. Each first micro-wire electrode 22 includes a
plurality of electrically connected first micro-wires 24. The first
electrode gaps 60 electrically isolate each of the first micro-wire
electrodes 22 from the other first micro-wire electrodes 22 and
each first micro-wire electrode 22 is connected to one of the wires
134 for controlling the first micro-wire electrode 22.
[0049] Referring to FIGS. 1B and 1D, a plurality of electrically
isolated second micro-wire electrodes 52 is located in a second
layer 50 in relation to the surface 12. The second layer 50 is at
least partially different from the first layer 20. Each second
micro-wire electrode 52 includes a plurality of electrically
connected second micro-wires 54. Micro-wire breaks 64 electrically
isolate each of the second micro-wire electrodes 52 from the other
second micro-wire electrodes 52 and each second micro-wire
electrode 52 is connected to one of the wires 134 for controlling
the second micro-wire electrode 52.
[0050] Referring to FIGS. 1C and 1D, a plurality of first gap
micro-wires 26 is located in each first electrode gap 60 in a gap
layer 80 different from the first layer 20 (FIG. 1A). The first
micro-wires 24 (FIG. 1A) and the first gap micro-wires 26 have the
same pattern (ignoring the micro-wire breaks 64). The first gap
micro-wires 26 are electrically isolated from the first micro-wires
24 in first micro-wire electrodes 22. In an embodiment, the first
gap micro-wires 26 include micro-wire breaks 64, as described
further below. In an embodiment, the first gap micro-wires 26 have
the same micro-wire pattern over the touch-sensitive area 32 (FIGS.
1A-1C) as the first micro-wires 24 so as to provide a uniform
optical appearance. In this embodiment, the first gap micro-wires
26 serve as dummy micro-wires to visually fill in the first
electrode gaps 60 between the first micro-wire electrodes 22 and
provide optical uniformity in the first electrode gaps 60.
[0051] As shown in FIGS. 1A, 1B, and 1C, the first and second
micro-wire electrodes 22, 52 overlap in a touch-sensitive area 32.
The overlapping portions of the first and second micro-wire
electrodes 22, 52 form capacitors whose capacitance is detectably
modified by the presence of a touching implement, such as a finger,
to form a touch-screen device.
[0052] In an embodiment, the first and second micro-wires 24, 54
are formed in a regular micro-wire pattern that extends over the
touch-sensitive area 32. In useful designs, the first electrode
gaps 60 are readily visible to the unaided human visual system
where the micro-wire breaks 64 are not when viewed at useful
distances. For example, the first electrode gaps 60 are 10-1,000
microns wide and the micro-wire breaks 64 are 0.1-10 microns
wide.
[0053] As shown in FIG. 1D with respect to the present invention,
first gap micro-wires 26 that are described as located within the
first electrode gap 60 are located within the first electrode gap
60 when viewed from a direction P perpendicular to the surface 12
so that the first gap micro-wires 26 appear between the first
electrode gaps 60. The first electrode gap 60 extends through
multiple layers in the direction P. As noted, the first gap
micro-wires 26 are in a separate gap layer 80 that is different
from the first layer 20 in the first electrode gap 60 but are not
in the first layer 20. Thus, as shown in FIG. 1D, the first gap
micro-wires 26 are located in the first electrode gaps 60 because,
as viewed from the direction P perpendicular to the surface 12, the
first gap micro-wires 26 appear between the first micro-wire
electrodes 22. In further embodiments, the first micro-wire
electrodes 22 extend in a first direction D1 parallel to the
surface 12, the second micro-wire electrodes 52 extend in a second
direction D2 parallel to the surface 12 and the first direction D1
is orthogonal to the second direction D2.
[0054] Referring to FIGS. 2A, 2B, 2C and 2D, in another embodiment
of the present invention, the gap layer 80 is the second layer 50,
the first gap micro-wires 26 are located within the second
micro-wire electrodes 52, and at least some of the first gap
micro-wires 26 are electrically connected to the second micro-wires
54. FIGS. 2A, 2B and 2C, are plan views of layers forming a
multi-layer structure. The layers are shown in combination in the
perspective of FIG. 2D.
[0055] As shown in FIG. 2D, the second layer 50 and the gap layer
80 are the same layer in relation to the surface 12 of the
substrate 10 and display 110. The second layer 50 includes both the
second micro-wires 54 and at least some of the first gap
micro-wires 26 in second micro-wire electrodes 52. The second
micro-wire electrodes 52 are electrically isolated from each other
by the micro-wire breaks 64 in the first gap micro-wires 26, as
illustrated in FIGS. 1A, 2A, 2B and 2C. The first micro-wire
electrodes 22 with the first micro-wires 24 separated by first
electrode gaps 60 are formed in a first layer 20 different from the
second layer 50 and gap layer 80. The embodiment of FIGS. 2A, 2B,
2C and 2D provides an electrical advantage in that the second
micro-wire electrodes 52 have improved electrical conductivity
because the first gap micro-wires 26 are located within the second
micro-wire electrodes 52 and are electrically connected to the
second micro-wires 54, as shown in FIGS. 2A and 2B
[0056] FIG. 2A illustrates both the second micro-wire electrodes 52
and the first gap micro-wires 26 in the second layer 50 so that the
second layer 50 is also the gap layer 80. The first gap micro-wires
26 are in the first electrode gap 60. The second micro-wires 54 of
the second micro-wire electrodes 52 are shown with solid lines and
the first gap micro-wires 26 are shown with dashed lines. Because
the second layer 50 includes both the second micro-wires 54 and at
least some of the first gap micro-wires 26, the second micro-wires
54 and at least some of the first gap micro-wires 26 are
electrically connected to form second micro-wire electrodes 52
having a variable micro-wire density along the length of the second
micro-wire electrodes 52. Note that the micro-wire breaks 64
illustrated in FIG. 1C in this embodiment electrically isolate each
of the second micro-wire electrodes 52 from the other second
micro-wire electrodes 52.
[0057] The elements and structures illustrated in FIG. 2B are
identical to those of FIG. 2A. The only difference in the Figures
is that the first gap micro-wires 26 are shown in FIG. 2B with
solid lines as are the second micro-wires 54 of the second
micro-wire electrodes 52 separated by the micro-wire breaks 64 in
the first gap micro-wires 26 in the first electrode gap 60. Both
the first gap micro-wires 26 and the second micro-wires 54 are in
the second layer 50 (which is also the gap layer 80).
[0058] Referring next to the plan view of FIG. 2C, the first
micro-wire electrodes 22 and the first micro-wires 24 separated by
the first electrode gaps 60 are added to the illustration of FIG.
2B to illustrate the micro-wire electrode structure 5. The first
micro-wires 24 of the first micro-wire electrodes 22 (illustrated
in FIG. 1A) are shown with dashed lines to distinguish them from
the second micro-wires 54 and the first gap micro-wires 26 of the
second micro-wire electrodes 52. The first micro-wire electrodes 22
are separated by the first electrode gaps 60 and the second
micro-wire electrodes 52 are separated by the micro-wire breaks 64
in the first gap micro-wires 26. Thus, in FIG. 2C, the micro-wires
illustrated with solid lines are those of the second layer 50 and
the micro-wires illustrated with the dashed lines are those of the
first layer 20 (see also FIG. 2D). The first and second micro-wire
electrodes 22, 52 overlap in the touch-sensitive area 32 to form
capacitors useful in a capacitive touch screen.
[0059] As shown in FIG. 2C, the second micro-wire electrodes 52 are
separated by the micro-wire breaks 64 in the first gap micro-wires
26 but otherwise have the same micro-wire pattern as the first
micro-wires 24 and first gap micro-wires 26 (and the first
micro-wire electrode 22) except that the second micro-wires 54 are
spatially offset in one dimension in a direction parallel to the
surface and are 180 degrees spatially out of phase with respect to
the first micro-wires 24.
[0060] The embodiment of FIGS. 2A, 2B, 2C and 2D provides an
electrical advantage in that the second micro-wire electrodes 52
have improved electrical conductivity because the first gap
micro-wires 26 of the first electrode gap 60 are connected to the
second micro-wires 54 of the second micro-wire electrodes 52 (FIG.
2B). Furthermore, the presence of additional first gap micro-wires
26 in the second micro-wire electrodes 52 reduces the interference
of electromagnetic radiation arising from sources below the second
layer 50 (e.g. the display 110) on the first micro-wire electrodes
22. Thus, if the first micro-wire electrodes 22 are used as sense
electrodes and the second micro-wire electrodes 52 are used as
drive electrodes in a capacitive touch screen, the sense electrode
(first micro-wire electrodes 22) have reduced noise and
interference and improved sensitivity.
[0061] FIGS. 1A, 1C, 3A, 3B, 3C and 3D are plan views of layers
forming a multi-layer structure according to embodiments of the
present invention. The layers are shown in different combinations
in the perspectives of FIGS. 3E and 3F. As noted above, the second
gap micro-wires 56 (FIGS. 3A-3D) are located in each second
electrode gap 62 when viewed from a direction orthogonal to the
surface 12 (FIG. 1D) and are not necessarily in a common layer with
the second micro-wires 54 and second micro-wire electrodes 52.
[0062] Referring next to FIG. 3A, in another embodiment the second
micro-wire electrodes 52 having the second micro-wires 54 are
spatially separated by second electrode gaps 62. A plurality of
second gap micro-wires 56 are located in each second electrode gap
62 and the second gap micro-wires 56 are electrically isolated from
the second micro-wires 54 by the micro-wire breaks 64. The second
gap micro-wires 56 have the same micro-pattern as the second
micro-wires 54, ignoring the micro-wire breaks 64.
[0063] Referring next to FIG. 3B, the first gap micro-wires 26
illustrated in FIG. 1C are located in the second layer 50 of FIG.
3A, have a common micro-pattern with the second micro-wires 54 and
second gap micro-wires 56, and at least some of the first gap
micro-wires 26 are electrically connected to the second micro-wires
54. The first gap micro-wires 26 that are within the area defined
by the second micro-wire electrodes 52 are electrically connected
to the second micro-wires 54 of the second micro-wire electrode 52.
The first gap micro-wires 26 that are not within the area defined
by the second micro-wire electrodes 52 are not electrically
connected to the second micro-wires 54 or the second micro-wire
electrode 52. Instead, they are located in the second electrode gap
62 and, in an embodiment, are electrically connected to the second
gap micro-wires 56.
[0064] In FIG. 3B, the second micro-wires 54 and the second gap
micro-wires 56 are shown with solid lines. The first gap
micro-wires 26 are shown with dashed lines. Because the first gap
micro-wires 26 in the second electrodes 52 are electrically
connected to the second micro-wires 54 they form a single electrode
with variable micro-wire density. Likewise, because the first gap
micro-wires 26 in the second electrode gap 62 are electrically
connected to the second gap micro-wires 56, they form a single
electrically conductive structure with variable micro-wire density.
The first gap micro-wires 26 in the first electrode gap 60 and the
second micro-wires 54 of the second micro-wire electrodes 52 are
electrically isolated from the first gap micro-wires 26 in the
first electrode gap 60 and the second gap micro-wires 56 in the
second electrode gaps 62 by micro-wire breaks 64.
[0065] FIG. 3C illustrates the identical elements and structures
illustrated in FIG. 3B. The only difference is that the first gap
micro-wires 26 in the first electrode gaps 60 are now shown with
solid lines as are the second micro-wires 54 of the second
micro-wire electrodes 52 and the second gap micro-wires 56 in the
second electrode gap 62. Both the first gap micro-wires 26 and the
second micro-wires 54 are in the second layer 50 (which is also the
gap layer 80).
[0066] Referring next to FIG. 3D, the first micro-wires 24 of the
first micro-wire electrodes 22 separated by first electrode gaps 60
(FIG. 1A) are incorporated into the micro-wire structure of FIG. 3C
to form a micro-wire electrode structure 5. In this illustration of
the micro-wire electrode structure 5, the first micro-wires 24 are
shown with dashed lines corresponding to the first layer 20 (e.g.
as in FIG. 2D). The first gap micro-wires 26, the second
micro-wires 54 of the second micro-wire electrodes 52 separated by
second electrode gaps 62, and the second gap micro-wires 56 are
shown with solid lines. The first gap micro-wires 26 and the second
micro-wires 54 of the second micro-wire electrodes 52 are
electrically connected to form an electrode with variable
micro-wire density (as shown more clearly in FIG. 3C that has
improved conductivity and performance. The second gap micro-wires
56 are electrically connected to first gap micro-wires 26 in the
second electrode gap 62 providing variable-density dummy
micro-wires that more readily shields electromagnetic
radiation.
[0067] FIG. 3E is a perspective of a combination of the layers
shown in FIG. 3D. In the embodiment of FIG. 3E, the second layer 50
(also the gap layer 80) is between the first layer 20 and the
surface 12 of substrate 10 and display 110. If the display 110
creates electromagnetic interference, according to an embodiment of
the present invention, the first gap micro-wires 26 (FIG. 3D) in
the second micro-wire electrodes 52 and the second electrode gap 62
shield the first micro-wire electrodes 22 in the first layer 20
separated by the first electrode gaps 60. The micro-wire breaks 64
prevent electrical shorts between the second micro-wire electrodes
52. Thus, signals sensed by the first micro-wire electrodes 22 have
an improved signal-to-noise ratio. A separate dielectric layer 40
is provided to separate the first and second micro-wire electrodes
22, 52. If the first layer 20 and second layer 50 are otherwise
electrically isolated (for example by portions of the first or
second layers 20, 50 as discussed further below), the dielectric
layer 40 is unnecessary.
[0068] In the embodiment illustrated in the perspective of FIG. 3F,
the first layer 20 is between the second layer 50 (which is also
the gap layer 80) and the surface 12 of substrate 10 and the
display 110. An unpatterned conductive layer 30 is in electrical
contact with the first micro-wires 24 (FIG. 3D) of the first
micro-wire electrodes 22 separated by first electrode gaps 60. A
separate optional dielectric layer 40 is provided to separate the
first micro-wire electrodes 22 from the second micro-wire
electrodes 52 and the unpatterned conductive layer 30 from the
second electrodes 52 separated by second electrode gaps 62. The
first and second micro-wire electrodes 22, 52 extend in directions
orthogonal to those of FIG. 3E. In general, the positions of the
first and second layers 20, 50 and the orientations and positions
of the first and second micro-wire electrodes 22, 52 can be
interchanged.
[0069] The unpatterned conductive layer 30 is an electrically
conductive layer with a relatively high resistance compared to the
first micro-wires 24 and the first micro-wire electrodes 22 and is
unpatterned within the touch-sensitive area 32 (FIG. 1A, 2C, 2D) so
that at least some electrical current can flow from one first
micro-wire electrode 22 to another first micro-wire electrode 22
through the unpatterned conductive layer 30. Thus, the first
micro-wire electrodes 22 are not completely electrically isolated
from each other. If the display 110 creates electromagnetic
interference, according to an embodiment of the present invention
the unpatterned conductive layer 30 shields the second micro-wire
electrodes 52 in the second layer 50. Thus, signals sensed by the
second micro-wire electrodes 52 have an improved signal-to-noise
ratio. In embodiments, the unpatterned conductive layer 30 is
patterned in areas outside the touch-sensitive area 32, for example
around the periphery of a touch screen.
[0070] In the embodiment illustrated in FIGS. 3A-3F, the first gap
micro-wires 26 and the second gap micro-wires 56 are located in the
second layer 50. In another embodiment, at least some of the second
gap micro-wires 56 are located in a layer different from the second
layer 50.
[0071] FIGS. 4A, 4B, 4C and 4D are plan views of various layers of
a micro-wire electrode structure 5 in various embodiments of the
present invention. Combinations of the layers are shown in FIGS. 3E
and 3F.
[0072] Referring first to FIG. 4A, the elements of FIG. 3A are
combined with the elements of FIG. 1C to form the micro-wire
electrode structure 5 of an embodiment of the present invention. As
shown in FIG. 4A, the first gap micro-wires 26 in the first
electrode gaps 60 between the first micro-wire electrodes 22 (FIG.
1A) are illustrated with dashed lines and the second micro-wires 54
and the second gap micro-wires 56 in the second electrode gap 62
between the second micro-wire electrodes 52 are illustrated with
solid lines.
[0073] FIG. 4B illustrates the identical elements and structures
illustrated in FIG. 4A. The only differences are that the first gap
micro-wires 26 are now shown with solid lines representing the
second layer 50 (FIG. 3E) as are the second micro-wires 54 of the
second micro-wire electrodes 52. The second gap micro-wires 56 in
the first micro-wire electrodes 22 (FIG. 1A) are now shown as
dashed lines representing the first layer 20 (FIG. 3E). The second
gap micro-wires 56 shown as dashed lines no longer include
micro-wire breaks 64 with the first micro-wires 24 (FIG. 1A) since,
as shown in FIG. 4C, the dashed second gap micro-wires 56 are in a
different layer from the second micro-wires 54 and the second gap
micro-wires 56 in the first electrode gap 60 and therefore will
maintain electrical isolation between the second micro-wire
electrodes 52. The absence of the micro-wire breaks 64 improves
both optical uniformity and resistance to electromagnetic radiation
interference.
[0074] FIG. 4C illustrates the structure of FIG. 4B with the
addition of the first microwire electrodes 22 and the first
micro-wires 24. In this Figure, the first micro-wires 24 of the
first micro-wire electrodes 22 and the second gap micro-wires 56 in
the area of the first micro-wire electrodes 22 that are not in both
the first and second electrode gaps 60, 62 are shown with dashed
lines that correspond to first micro-wire electrodes 22 in the
first layer 20 (FIGS. 3E and 3F) and are separately shown in FIG.
4D. FIG. 4D shows the first micro-wire electrodes 22 with the first
micro-wires 24 and the second gap micro-wires 56 in the area of the
first micro-wire electrodes 22 forming the first micro-wire
electrodes 22 with variable micro-wire density.
[0075] As shown in FIG. 4C, the second micro-wires 54 and the first
gap micro-wires 26 of the second micro-wire electrodes 52 are shown
with solid lines. The first and second gap micro-wires 26, 56 in
both the first and second electrode gaps 60, 62 are also shown with
solid lines. Solid-line micro-wires correspond to the second layer
50 (FIGS. 3E and 3F). Both the dielectric layer 40 (FIGS. 3E and
3F) and the unpatterned conductive layer 30 (FIG. 3F) are useful
with the layers illustrated in FIG. C in the structures illustrated
in either FIG. 3E or FIG. 3F.
[0076] The micro-wire electrode structure 5 of FIG. 4C electrically
connects the first gap micro-wires 26 that are in the area of the
second micro-wire electrodes 52 to the second micro-wires 54 to
form more conductive second micro-wire electrodes 52 (shown in FIG.
4B). Similarly, the second gap micro-wires 56 that are in the area
of the first micro-wire electrodes 22 are electrically connected to
the first micro-wires 24 (as shown in FIG. 4D). Those first gap
micro-wires 26 and second gap micro-wires 56 that are in neither of
the areas of the first or second micro-wire electrodes 22, 52 and
are therefore in both the first and second electrode gaps 60, 62,
shown as dummy-wire area 36, are electrically connected and can
serve as an electromagnetic interference shield for the first or
second micro-wire electrodes 22, 52. Thus, at least some of the
dummy micro-wires of the first layer 20 (first gap micro-wires 26)
serve as second micro-wire electrode 52 micro-wires. Likewise, at
least some of the dummy micro-wires of the second layer 50 (second
gap micro-wires 56) serve as second micro-wire electrode 52
micro-wires. Those first gap micro-wires 26 and second gap
micro-wires 56 that are located in both the first and second
electrode gaps 60, 62 are therefore dummy wires electrically
isolated from both the first and second micro-wire electrodes 22,
52.
[0077] In one embodiment, the first or second gap micro-wires 26,
56 in the dummy-wire area 36 are located in the second layer 50 (as
shown in FIGS. 4C, 3E, and 3F), but in another embodiment are in
the first layer 20. In the case in which an unpatterned conductive
layer 30 is provided to electrically connect the first micro-wires
24, the first or second gap micro-wires 26, 56 in the dummy-wire
area 36 are located in the second layer 50 to avoid electrically
shorting the unpatterned conductive layer 30.
[0078] By locating the second gap micro-wires 56 in the area of the
first micro-wire electrodes 22 in a different layer from the other
second gap micro-wires 56 (those in the dummy-wire area 36), the
conductivity of the first micro-wire electrodes 22 is improved.
However, those second gap micro-wires 56 in the area of the first
micro-wire electrodes 22 do not then serve as electromagnetic
interference shields as do the second gap micro-wires in the
dummy-wire area 36. Thus, the embodiment of FIG. 4C compared to the
embodiment of FIG. 3D represents a different tradeoff between
electrode conductivity and electromagnetic interference
shielding.
[0079] In an embodiment of the present invention, the first
micro-wire electrodes 22 are the drive electrodes of a capacitive
touch screen and the second micro-wire electrodes 52 are the sense
electrodes of the capacitive touch screen. Alternatively, the first
micro-wire electrodes 22 are the sense electrodes of a capacitive
touch screen and the second micro-wire electrodes 52 are the drive
electrodes of the capacitive touch screen. The present invention
includes a capacitive touch screen having the first and second
micro-wire electrodes 22, 52 and first or second gap micro-wires
26, 56, as described above.
[0080] Referring to FIGS. 5 and 7, a method of making a micro-wire
electrode structure 5 of the present invention includes providing
the substrate 10 having the surface 12 in step 200. A first layer
20 is provided in relation to the surface 12 in step 205 and a
plurality of first micro-wire electrodes 22 spatially separated by
first electrode gaps 60 is located in the first layer 20 in step
210. Each first micro-wire electrode 22 includes a plurality of
electrically connected first micro-wires 24. A second layer 50 is
provided in relation to the surface 12 in step 215 and a plurality
of electrically isolated second micro-wire electrodes 52 is located
in the second layer 50 in step 220. The second layer 50 is at least
partially different from the first layer 20 and each second
micro-wire electrode 52 includes a plurality of electrically
connected second micro-wires 54. A gap layer 80 different from the
first layer 20 is provided in step 225 and a plurality of first gap
micro-wires 26 is located in each first electrode gap in step 230.
At least some of the first gap micro-wires 26 are located in the
gap layer 80. The first gap micro-wires 26 are electrically
isolated from the first micro-wires 24. As shown in FIG. 5, in an
embodiment the second layer 50 and the gap layer 80 are the same
layer and the step 215 of providing the second layer 50 is the same
as the step 225 of providing the gap layer 80. Moreover, at least
some of the first gap micro-wires 26 and the second micro-wires 54
are located in the same second layer 50 (and gap layer 80). In
another embodiment, the step 220 of locating the second micro-wires
54 is the same as step 230 of locating the first gap micro-wires
26.
[0081] In additional embodiments of the present invention, a
dielectric layer 40 is provided between the first and second layer
20, 50. In another embodiment, a protective overcoat layer 70 is
provided over the second layer 50 to protect the micro-wire
electrode structure 5 of the present invention and provide a touch
surface 11.
[0082] Referring to FIGS. 6 and 8, another method of making a
micro-wire electrode structure 5 of the present invention locates
the first and second layers 20, 50 in an opposite order with
respect to the surface 12. Such an embodiment includes providing
the substrate 10 having the surface 12 in step 200. A second layer
50 is provided in relation to the surface 12 in step 215 and a
plurality of second micro-wire electrodes 52 is located in the
second layer 50 in step 250. Each second micro-wire electrode 52
includes a plurality of electrically connected second micro-wires
54 and first gap micro-wires 26. A first layer 20 is provided in
relation to the surface 12 in step 205 and a plurality of
electrically isolated first micro-wire electrodes 22 spatially
separated by first electrode gaps 60 is located in the first layer
20 in step 210. The first layer 20 is at least partially different
from the second layer 50 and each first micro-wire electrode 22
includes a plurality of electrically connected first micro-wires
24. The second layer 50 also serves as the gap layer 80 different
from the first layer 20 and includes the first gap micro-wires 26.
The first gap micro-wires 26 are electrically isolated from the
first micro-wires 24. An optional protective overcoat layer 70 is
provided over the second layer 50 to protect the micro-wire
electrode structure 5 and provide a touch surface 11.
[0083] Referring to FIG. 5 again and to FIG. 9, another method of
making a micro-wire electrode structure 5 of the present invention
includes providing the substrate 10 having the surface 12 in step
200. A first layer 20 is provided in relation to the surface 12 in
step 205 and a plurality of first micro-wire electrodes 22
spatially separated by first electrode gaps 60 is located in the
first layer 20 in step 210. Each first micro-wire electrode 22
includes a plurality of electrically connected first micro-wires
24. An unpatterned conductive layer 30 is optionally provided in
electrical contact with the first micro-wire electrodes 22 in step
260. In one embodiment, the first layer 20 is located between the
unpatterned conductive layer 30 and the surface 12 (as shown in
FIG. 5). In another embodiment, the unpatterned conductive layer 30
is located between the first layer 20 and the surface 12 (not
shown). In one embodiment, the unpatterned conductive layer 30 and
first layer 20 are located between the second layer 50 and the
surface 12 (as shown in FIG. 5). Alternatively, the second layer 50
is located between the surface 12 and both the unpatterned
conductive layer 30 and the first layer 20 (not shown, but FIG. 6
illustrates the second layer 50 between the first layer 20 and the
surface 12). In an embodiment, the unpatterned conductive layer 30
is used in the structure of FIG. 6, for example by locating the
unpatterned conductive layer 30 between the first layer 20 and the
protective overcoat layer 70.
[0084] In yet another embodiment, an optional dielectric layer 40
is optionally located in contact with the unpatterned conductive
layer 30 in step 270. In other embodiments, a portion of the first
or second layers 20, 50 serves to electrically isolate micro-wires
in the first layer 20 from micro-wires in the second layer 50 (e.g.
as shown in FIG. 6). A second layer 50 is provided in relation to
the surface 12 in step 215 and a plurality of second micro-wire
electrodes 52 and first gap micro-wires 26 are located in the
second layer 50 in a common step 250.
[0085] Referring to FIG. 4C, FIG. 5, and to FIG. 10, in an
alternative embodiment a method of making a micro-wire electrode
structure 5 of the present invention includes providing the
substrate 10 having the surface 12 in step 200. A first layer 20 is
provided in relation to the surface 12 in step 205 and a plurality
of first micro-wire electrodes 22 spatially separated by first
electrode gaps 60 is located in the first layer 20 in step 280.
Each first micro-wire electrode 22 includes a plurality of
electrically connected first micro-wires 24 and at least some
second gap micro-wires 56 located at the same time in the same step
280. A second layer 50 is provided in relation to the surface 12 in
step 215 and a plurality of second micro-wire electrodes 52
spatially separated by second electrode gaps 62 is located in the
second layer 50 in step 250. Each second micro-wire electrode 52
includes a plurality of electrically connected second micro-wires
54 and at least some first gap micro-wires 26 located at the same
time in the same step 250.
[0086] In useful embodiments of the present invention, in step 250
the second micro-wire electrodes 52 are formed in a single step in
the second layer 50 so that the second micro-wires 54 and first gap
micro-wires 26 are likewise formed in a single step and are formed
from a common material. Likewise, in step 280 the first micro-wire
electrodes 22 are formed in a single step in the first layer 20 so
that the first micro-wires 24 and second gap micro-wires 56 are
formed in a single step and are formed from a common material.
[0087] In an embodiment, the unpatterned conductive layer 30 in
electrical contact with the first micro-wires 24 of the first
micro-wire electrodes 22 is provided before the second layer 50 is
located. In other embodiments of the present invention, the first
layer 20 is located with respect to the surface 12 before the
second layer 50 is provided. For example, the first layer 20 is
formed on the surface 12 and the second layer 50 is subsequently
formed on the first layer 20, or on layers such as the unpatterned
conductive layer 30 or dielectric layer 40 formed on the first
layer 20, so that the first layer 20 is between the surface 12 and
the second layer 50. Alternatively, the second layer 50 is located
with respect to the surface 12 before the first layer 20 is
provided. For example, the second layer 50 is formed on the surface
12 and the first layer 20 is subsequently formed on the second
layer 50, or on layers such as the unpatterned conductive layer 30
or dielectric layer 40 formed on the second layer 50, so that the
second layer 50 is between the surface 12 and the first layer
20.
[0088] In a further embodiment of a method of the present
invention, a display substrate or a display cover having the
surface 12 is provided so that the display cover or display
substrate is the substrate 10. Alternatively, the substrate 10 is
affixed to the display 110. In an embodiment, the display 110 is a
source of electromagnetic radiation.
[0089] In yet another embodiment, the micro-wire electrode
structure 5 is peeled from the substrate 10 and applied to another
substrate, such as the display substrate or display cover. The
micro-wire electrode structure 5 is applied with either side
adjacent to the other substrate, effectively enabling a reversal of
layer order with respect to the other substrate. In such a
structure, the end result is that the first and second micro-wires
24, 25 are effectively located at the bottom of their respective
first and second layers 20, 50.
[0090] Referring to FIG. 14, the structure of FIG. 6 is constructed
with the unpatterned conductive layer 30 in place of the overcoat
layer 70 (FIG. 6) in electrical contact with the first micro-wire
electrodes 22 and first micro-wires 24 in first layer 20 separated
by first electrode gaps 60. The micro-wire electrode structure 5 is
peeled from the surface 12 of the substrate 10 (FIG. 6) and applied
to another substrate (shown as the display 110) with the
unpatterned conductive layer 30 in contact with the other substrate
and the second layer 50 (also the gap layer 80) with second
micro-wire electrodes 52 having second micro-wires 54 and first gap
micro-wires 26 on the opposite side of the first layer 20.
[0091] In a useful embodiment that provides optical uniformity, the
first micro-wire electrodes 22 are provided in a first
micro-pattern that is similar to a second micro-pattern in which
the second micro-wires 54 are provided but offset from the first
micro-pattern in a direction parallel to the surface by a spatial
phase difference of 180 degrees.
[0092] In various embodiments of the present invention, various
layers are formed from a curable material, such as a polymer or
resin that is coated in a liquid form and then cured to form a
solid, for example by exposure to ultra-violet radiation or heat.
Curable materials can include cross-linking materials.
[0093] According to various embodiments of the present invention,
micro-wires are provided in association with layers in various
ways. In one embodiment, micro-wires are formed on a layer surface,
for example by printing on surface 12 and then coated with a
curable layer that is then cured. In such an embodiment, the
micro-wires are located at the bottom of the layer. In another
embodiment, conductive ink is printed, for example by inkjet,
gravure, or flexographic printing, on top of a layer surface and
then cured. Alternatively, micro-channels are imprinted in an
uncured layer, the layer is cured, and then conductive ink supplied
in the micro-channels and cured to form micro-wires. In yet another
method, layers are laminated together. Laminated layers can include
micro-wires in a pre-formed pattern. Coating methods such as spin
coating, curtain coating, slot coating, extrusion coating, and
hopper coating are known in the art as are printing methods such as
ink jet, gravure, and flexographic printing. Lamination methods are
well known. Conductive inks are also known as are method for
imprinting and filling micro-channels.
[0094] First micro-wires 24 can extend partially or all of the way
through the first layer 20. The unpatterned conductive layer 30 and
the first layer 20 can be the same common layer and first
micro-wires 24 formed in, on, or under the common layer. The
unpatterned conductive layer 30 and the first layer 20 can be
coated together, for example with slot or extrusion coating. The
first or second layers 20, 50 can be imprinted with a stamp having
protrusions as deep as or deeper than the depth of the respective
layers. The unpatterned conductive layer 30 can be coated on the
first layer 20 and in contact with the first micro-wires 24. In an
embodiment, the first or second layers 20, 50 are cured to form
micro-channels that are filled with conductive ink and to form
first or second micro-wires 24, 54. The dielectric layer 40, second
layer 50, or overcoat layer 70 are also formed using known coating
methods.
[0095] In embodiments of the present invention, the electrical
resistance of the unpatterned conductive layer 30 is greater than
the resistance of each of the first or second micro-wire electrodes
22, 52. In tests, the resistance of the unpatterned conductive
layer 30 was measured as the sheet resistance of the unpatterned
conductive layer 30 independently of the first or second
micro-wires 24, 54. The resistance of the first or second
micro-wire electrodes 22, 52 is the resistance measured along the
length of the first or second micro-wire electrodes 22, 52.
[0096] In an embodiment, the unpatterned conductive layer 30 has a
sheet resistance greater than 1 k.OMEGA. per square, greater than
10 k.OMEGA. per square, greater than 100 k.OMEGA. per square,
greater than 1 M.OMEGA. per square, greater than 10 M.OMEGA. per
square, greater than 100 M.OMEGA. per square, greater than 1
G.OMEGA. per square, greater than 10 G.OMEGA. per square, or
greater than 100 G.OMEGA. per square. This lower limit in
resistivity of the unpatterned conductive layer 30 is dependent in
part on the frequency at which the first or second micro-wire
electrodes 22, 52 are driven and on the touch-screen controller 140
current and voltage characteristics and on the conductivity of the
first or second micro-wire electrodes 22, 52.
[0097] In another embodiment, the resistance of the unpatterned
conductive layer 30 between any two first micro-wire electrodes 22
is at least five times greater, at least ten times greater, at
least twenty times greater, at least fifty times greater, at least
100 times greater, at least 500 times greater, at least 1,000 times
greater, at least 10,000, at least 100,000, or at least 1,000,000
times greater than the resistance of either of the any two first
micro-wire electrodes 22. In one embodiment, the resistance of the
unpatterned conductive layer 30 between the first micro-wire
electrodes 22 separated by the first electrode gap 60 is at least
ten times greater than the resistance of any of the first
micro-wire electrodes 22.
[0098] In a further embodiment of the present invention, the
touch-screen controller 140, for example an integrated circuit, for
driving the first micro-wire electrodes 22 provides voltage and
current to the first micro-wire electrodes 22 in a desired driver
waveform having a period and frequency. The frequency of the driver
waveform limits the rate at which the capacitance between the first
and second micro-wire electrodes 22, 52 can be measured. Because
the unpatterned conductive layer 30 is electrically connected to
the first micro-wire electrode 22 and has a limited conductivity,
the rate at which the first micro-wire electrode 22 and the
unpatterned conductive layer 30 can be charged is likewise limited.
A micro-wire electrode, such as the first micro-wire electrode 22,
has open areas between the micro-wires in the micro-wire electrode
that, according to the present invention, are filled with
conductive material in the unpatterned conductive layer 30. Thus,
the conductivity of the unpatterned conductive layer 30 will
define, in combination with the open area defined by the geometry
of the first micro-wires 24 in the first micro-wire electrode 22,
the rate at which the first micro-wire electrode 22 and the
unpatterned conductive layer 30 can be charged or discharged.
Therefore, the conductivity of the unpatterned conductive layer 30
and the open area define the time constant for charging or
discharging the first micro-wire electrode 22 and the center of the
open area in response to a voltage change as provided by the driver
waveform. Therefore, according to the further embodiment of the
present invention, the sheet resistance of the unpatterned
conductive layer 30 is sufficiently low that the time constant for
charging the center of the open area between first micro-wires 24
in the first micro-wire electrode 22 is less than the period of a
driver waveform. In another embodiment, the time constant is
substantially less than the period. By substantially less is meant
at least 5% less, at least 10% less, at least 20% less, or at least
50% less.
[0099] In operation, a touch-screen controller (for example
touch-screen controller 140 of FIG. 11) energizes one of the first
micro-wire electrodes 22 with a signal and senses one of the second
micro-wire electrode 52 to detect the capacitance or changes in
capacitance of the area overlapped by the one first micro-wire
electrode 22 and one second micro-wire electrode 52. For such an
application, the first micro-wire electrodes 22 extending in a
first direction parallel to the surface 12 are located orthogonally
to the second micro-wire electrodes 52 extending in a second
direction D2 parallel to the surface and orthogonal to the first
direction D1.
[0100] Since the unpatterned conductive layer 30 electrically
connects the first micro-wire electrodes 22, some current leaks
from the driven first micro-wire electrode 22 to other first
micro-wire electrodes 22. However, because the resistance of the
unpatterned conductive layer 30 is high relative to the resistance
of the first micro-wire electrodes 22, capacitance is still
detected in the overlapped electrode area. Moreover, the presence
of the unpatterned conductive layer 30 inhibits electromagnetic
interference from affecting the capacitance measure by the second
micro-wire electrode 52, especially if the electromagnetic
interference originates from a side of the unpatterned conductive
layer 30 opposite the second micro-wire electrodes 52. Furthermore,
the unpatterned conductive layer 30 assists in extending the
electrical field produced by driving the first micro-wires 24 in
the one first micro-wire electrode 22 into the spaces between the
first micro-wires 24, thereby providing a more uniform field
between the first micro-wire electrode 22 and the second micro-wire
electrode 52. A more uniform field enables a more consistent and
sensitive detection of capacitance changes due to the presence of
perturbing elements such as a finger or a stylus at varying spatial
locations. Furthermore, the presence of the unpatterned conductive
layer 30 reduces the sensitivity of the touch-screen device to
differences in alignment between the micro-wires of the first
micro-wire electrodes 22 and the second micro-wire electrodes
52.
[0101] In comparison to other prior-art solutions using a separate
ground plane beneath driver or sensor electrodes to reduce the
effect of electro-magnetic radiation, for example from a display
located beneath the touch screen, the present invention provides a
thinner touch-screen and display structure with fewer layers.
[0102] A variety of techniques are usable to construct a touch
screen device of the present invention. In various embodiments, the
patterned first micro-wire electrodes 22 are formed in a layer,
such as first layer 20, unpatterned conductive layer 30, or
dielectric layer 40, printed or transferred onto a layer, such as
the substrate 10, unpatterned conductive layer 30, or dielectric
layer 40, or laminated on the substrate 10 or other layer on the
substrate 10. In other embodiments, the unpatterned conductive
layer 30 is laminated, coated, formed by evaporation, sputtering,
or chemical vapor deposition, or formed by atomic layer deposition
on the first micro-wire electrodes 22 or first layer 20 or on the
second layer 50. The dielectric layer 40 is laminated, coated,
formed by evaporation, sputtering, or chemical vapor deposition, or
formed by atomic layer deposition on the unpatterned conductive
layer 30. The patterned second micro-wire electrodes 52 are formed
in a layer, such as second layer 50 or dielectric layer 40, printed
or transferred onto a layer, such as the substrate 10 or dielectric
layer 40, or laminated on the substrate 10 or other layer on the
substrate 10.
[0103] In an embodiment, unpatterned conductive layer 30 or
dielectric layer 40 is deposited by sputtering or deposition and
patterned outside the touch-sensitive area 32 either with masks or
by photolithographic processes. In an embodiment, conductive
material is only deposited in the touch-sensitive area 32.
Alternatively, conductive material is deposited over the entire
substrate 10 and removed as needed, for example in peripheral
regions of the touch screen outside the touch-sensitive area 32. 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 outside the touch-sensitive area 32 is accomplished, for
example, by masking the deposition, using patterned deposition
inhibitors, or by photolithographic processes.
[0104] In an embodiment, the substrate 10 and the surface 12 are
provided in step 200, together with imprinting stamps. The first
layer 20 is provided on the substrate 10 and surface 12 in step
205, for example by coating. The patterned first micro-wire
electrodes 22 are formed by imprinting the first layer 20 with an
imprinting stamp, curing the first layer 20 to form the first
micro-channels that are filled with conductive ink. The conductive
ink is cured to form first micro-wires 24 and optional second gap
micro-wires 56 located in the first micro-channels in step 210 or
step 280. The unpatterned conductive layer 30 is coated over the
first micro-wires 24 in step 260 and the optional dielectric layer
40 is optionally coated over the unpatterned conductive layer 30 in
step 270. The patterned second micro-wire electrodes 52 are formed
by coating and imprinting the second layer 50 with an imprinting
stamp, curing the second layer 50 to form second micro-channels
that are filled with conductive ink. The conductive ink is cured in
step 250 to form the second micro-wires 54 and form the first gap
micro-wires 26.
[0105] In other embodiments, imprinting methods are used to imprint
first micro-channels in the dielectric layer 40 or in the
unpatterned conductive layer 30. Similarly, in other embodiments
imprinting methods are used to imprint second micro-channels in the
dielectric layer 40.
[0106] Printing methods are usable in other embodiments of the
present invention. A conductive ink is printable, for example with
a flexographic plate, on a substrate 10 or other layer and cured to
form micro-wires. Alternatively, a pattern of micro-wires is
transferrable to the substrate 10 or other layer from another
substrate.
[0107] In an alternative embodiment, micro-wires are formed by
coating a flexographic substrate having a raised pattern
corresponding to a desired micro-wire pattern with a conductive
ink. The flexographic substrate is brought into contact with a
layer surface to print the conductive ink onto the layer surface.
In an optional step, the conductive ink is dried. Flexographic
substrates are known in the flexographic printing arts.
[0108] Transferred or printed micro-wires can be coated with
curable material to form the first layer 20 or second layer 50. The
first layer 20 or second layer 50 can also be the dielectric layer
40. In an embodiment, the unpatterned conductive layer 30 is the
first layer 20.
[0109] In yet another embodiment, layer structures are laminated to
another layer. For example, the first layer 20 is made as a
separate construction (for example as a layer of PET) including
first micro-wires 24 and then laminated with an adhesive to
substrate 10. Second layer 50 is made and similarly laminated. The
unpatterned conductive layer 30 or dielectric layer 40 can be
laminated onto their respective layers, together or separately. In
another embodiment, a layer structure is formed on a temporary
substrate with a temporary adhesive on a first side, the layer
structure is permanently adhered to the substrate 10 or layer
formed on the substrate 10 on a second side, and then the temporary
substrate is removed from the first side, for example by
peeling.
[0110] In various embodiments, the unpatterned conductive layer 30
is laminated, coated, or deposited on the first micro-wire
electrodes 22. In an embodiment, atomic layer deposition is used to
form the unpatterned conductive layer 30. In other embodiments, the
dielectric layer 40 is laminated, coated, or deposited on the first
micro-wire electrodes 22.
[0111] Dielectric layer 40 can be any of many known dielectric
materials included polymers or oxides and are deposited or formed
in any of a variety of known ways, including pattern-wise inkjet
deposition, sputtering, or coating through a mask or blanket coated
and patterned using known photo-lithographic methods. Such known
photo-lithographic technology can include a photosensitive material
that is optically patterned through a mask to cure the
photosensitive material and removal of either the cured or the
uncured material.
[0112] In an embodiment, unpatterned conductive layer 30 is
transparent and includes one or more of a variety of transparent
conductive materials, for example organic conductive polymers such
as Poly(3,4-ethylenedioxythiophene) (PEDOT),
Poly(3,4-ethylenedioxythiophene) PEDOT: poly(styrene sulfonate)
PSS, Poly(4,4-dioctylcyclopentadithiophene), and Polypyrrole (PPy),
long-chain aliphatic amines (optionally ethoxylated) and amides,
quaternary ammonium salts (such as, behentrimonium chloride or
cocamidopropyl betaine), esters of phosphoric acid, polyethylene
glycol esters, or polyols, polyaniline nanofibers, carbon
nanotubes, graphene, metals such as silver nanowires, and inorganic
conductive oxides such as ITO, SnO.sub.2, In.sub.2O.sub.3, ZnO,
Aluminum-doped zinc oxide (AZO), CdO, Ga.sub.2O.sub.3,
V.sub.2O.sub.5. Deposition methods for conductive materials can
include solvent or aqueous coating, printing by for example inkjet,
gravure, offset litho, flexographic, or electro-photographic,
lamination, evaporation, chemical vapor deposition (CVD),
sputtering, atomic-layer deposition (ALD) or spatial-atomic-layer
deposition (SALD).
[0113] In another embodiment, unpatterned conductive layer 30 is an
ionic conductor, a solid ionic conductor, an electrolyte, a solid
electrolyte, or a conductive gel, as are known in the art.
[0114] In an embodiment, the unpatterned conductive layer 30 has a
thickness less than or equal to 50 nm, 100 nm, 200 nm, 500 nm, or 1
micron. In other embodiments, the unpatterned conductive layer 30
has a thickness less than or equal to 10 microns, 100 microns, 200
microns, 500 microns, or 1 mm.
[0115] According to various embodiments of the present invention,
the substrate 10 is any material on which a layer is formed. The
substrate 10 is a rigid or a flexible substrate made of, for
example, a glass, metal, plastic, or polymer material, is
transparent, and can have opposing substantially parallel and
extensive surfaces. The substrates 10 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 10 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.
[0116] In various embodiments the substrate 10 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. In an
embodiment, the substrate 10 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 or otherwise form layers. In a useful embodiment, the
substrate 10 is substantially transparent, for example having a
transparency of greater than 90%, 80% 70% or 50% in the visible
range of electromagnetic radiation.
[0117] Electrically conductive micro-wires and methods of the
present invention are useful for making electrical conductors and
buses for transparent micro-wire electrodes and electrical
conductors in general, for example as used in electrical buses. A
variety of micro-wire patterns are used and the present invention
is not limited to any one pattern. Micro-wires can be spaced apart,
form separate electrical conductors, or intersect to form a mesh
electrical conductor on, in, or above the substrate 10.
Micro-channels can be identical or have different sizes, aspect
ratios, or shapes. Similarly, micro-wires can be identical or have
different sizes, aspect ratios, or shapes. Micro-wires can be
straight or curved.
[0118] A micro-channel is a groove, trench, or channel formed on or
in a layer extending from the surface of the layer 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, the cross-sectional depth of a
micro-channel is comparable to its width. Micro-channels can have a
rectangular cross section. 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. Micro-channels are not distinguished in the Figures from
the micro-wires.
[0119] Imprinted layers 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 imprinting stamp having an inverse micro-channel structure is
applied to liquid curable material and the cross-linking agents in
the curable material are activated, the liquid curable material in
the curable layer is hardened into a cured layer with imprinted
micro-channels. The liquid curable materials can include a
surfactant to assist in controlling coating. Materials, tools, and
methods are known for embossing coated liquid curable materials to
form cured layers.
[0120] A cured layer is a layer of curable material that has been
cured. For example, a cured layer is formed of a curable material
coated or otherwise deposited on a layer surface to form a curable
layer and then cured to form the cured layer. The coated curable
material is considered herein to be a curable layer before it is
cured and cured layer after it is cured. Similarly, a cured
electrical conductor is an electrical conductor formed by locating
a curable material in micro-channel and curing the curable material
to form a micro-wire in a micro-channel. 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.
[0121] The curable layer is deposited as a single layer in a single
step using coating methods known in the art, such as curtain
coating. In an alternative embodiment, the curable layer is
deposited as multiple sub-layers using multi-layer deposition
methods known in the art, such as 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.
[0122] 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. 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.
[0123] Curable inks provided in a liquid form are deposited or
located in first or second micro-channels and cured, for example by
heating or exposure to radiation such as infra-red radiation,
visible light, or ultra-violet radiation. The curable ink hardens
to form the cured ink that makes up first or second micro-wires 24,
54. For example, a curable conductive ink with conductive
nano-particles are located within first or second micro-channels
and cured by heating or sintering to agglomerate or weld the
nano-particles together, thereby forming an electrically conductive
first or second micro-wire 24, 54. Materials, tools, and methods
are known for coating liquid curable inks to form micro-wires.
[0124] 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 and heated or dried to
remove liquid carrier or treated with hydrochloric acid, leaving a
porous assemblage of conductive particles that are 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.
[0125] 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 the micro-wire formation process.
[0126] In various embodiments of the present invention,
micro-channels or micro-wires have 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 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-wires can fill micro-channels; in other embodiments
micro-wires do not fill micro-channels. In an embodiment, the
micro-wires are solid; in another embodiment, the micro-wires are
porous.
[0127] Micro-wires 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 can include a thin
metal layer composed of highly conductive metals such as gold,
silver, copper, or aluminum. Other conductive metals or materials
are usable. Alternatively, micro-wires 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 with
pattern-wise deposition or pattern-wise formation followed by
curing steps. Other materials or methods for forming micro-wires,
such as curable ink powders including metallic nano-particles, are
employed and are included in the present invention.
[0128] Electrically conductive micro-wires of the present invention
are operable by electrically connecting micro-wires through
connection pads and electrical connectors to electrical circuits
that provide electrical current to micro-wires and can control the
electrical behavior of micro-wires. Electrically conductive
micro-wires 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 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.
Inventive Example:
[0129] The second micro-wire electrodes 52 including the second
micro-wires 54 but excluding the first gap micro-wires 26 were
prepared using a standard lithographic process. Microposit 1813
photoresist was spin-coated onto a 1000 .ANG. thermally deposited
aluminum layer coated on a 2.5 inch by 2.5 inch square 4 mil PET
support. The photoresist was exposed to UV light through a
chrome-on-quartz mask, developed, rinsed and dried. The film was
then etched in PAN etch leaving a positive image having 10 .mu.m
wide aluminum micro-wires forming connected open
right-angle-diamond electrodes, 1600 .mu.m on diagonal. The
periodic width of the second micro-wire electrodes 52 was 6.42 mm
separated by 400 micron micro-wire breaks 64 in the second
micro-wires 54 at intersections between the second micro-wire
electrodes 52. The second micro-wire electrodes 52 were terminated
with conductive rectangular pads to enable simple resistance
measurements end-to-end. The pads at one end of the second
micro-wire electrodes 52 also had conductive bus lines leading to
additional pads at the edge of the support (the dielectric layer
40) to enable conventional 1 mm pitch edge connection with
electrical test fixtures. The photoresist was removed with acetone
and methanol baths and dried with nitrogen. The second micro-wire
electrode 52 resistance was measured to be on the order of
450.OMEGA. from end-to-end and essentially infinite between nearest
neighbor electrodes.
[0130] The first micro-wire electrodes 22 including the first
micro-wires 24 but excluding the second gap micro-wires 56 were
prepared as were the second micro-wire electrodes 52, on a separate
4 mil PET support (substrate 10), and with the final addition of a
transparent unpatterned conductive layer 30 formed on the
lithographically patterned first micro-wires 24 by spin coating a
solution of PEDOT/PSS at 3000 rpm and drying on a hotplate for 2
minutes at 110.degree. C. Sheet resistance of the dried PEDOT/PSS
coating on a section of bare PET support using a four-point probe
was 8 M.OMEGA./square. First electrode resistance was measured to
be on the order of 450.OMEGA. from end-to-end with approximately
160 k.OMEGA. between nearest neighbor electrodes. Thus the ratio of
shorting resistance to first electrode resistance in this inventive
example was 356 to 1.
[0131] A functional touch-screen was fabricated from the prepared
second and first micro-wire electrodes 52, 22 by first laminating a
cover sheet of 4 mil PET (overcoat layer 70) on the exposed side of
the second micro-wire electrodes 52 on dielectric layer 40 using
optically clear adhesive, OCA (Adhesives Research, ARClear 8154
Optically Clear Unsupported Transfer Adhesive) to form a coversheet
(overcoat layer 70) of the touch-screen example. The second
micro-wire electrodes 52 were oriented 90 degrees with respect to
the first micro-wire electrodes 22 and offset such that the
intersections of the diamonds were directly above the center of the
diamonds of the first micro-wire electrodes 22. The uncoated side
of the dielectric layer 40 was laminated to the exposed side of the
unpatterned conductive layer 30 using the same optically clear
adhesive. The dielectric thus includes both the OCA and the 4 mil
PET dielectric layer 40.
Comparative Example
[0132] For the purpose of comparison, a control touch-screen
representing an example of the prior art was prepared exactly as
described above except the coating of PEDOT/PSS forming the
unpatterned conductive layer 30 was eliminated in the comparative
example.
Results:
[0133] The measurement apparatus included two translation stages
which were used to move a mechanical, artificial finger
incrementally across the sample. The weight of the finger was used
to provide a constant touch force and the tip of the artificial
finger included a compliant, conductor loaded, polymer foam mounted
on the end of a conductive rod. All but one first micro-wire
electrode 22 were held at ground while a voltage waveform including
a controlled burst of sine waves (either 100 kHz or 1 MHz) was
applied to one of the first micro-wire electrodes 22. All of the
second micro-wire electrodes 52 were held at ground and one was
connected to a charge sensitive pre-amplifier (operational
amplifier with capacitor feedback) which held the second micro-wire
electrodes 52 at ground and output a voltage proportional to the
input charge. The output voltage from the sensing amplifier was
sampled periodically at 20 MHz. Digital processing was used to
synchronously (with respect to the driven waveform) rectify the
sampled signal and compute an average (in phase) voltage. By
spatially stepping the artificial finger across the sample in a
spatial matrix of locations, the sensed voltages are mapped as a
function of the artificial finger location. By inference, the
response of a single repetitive unit at a single location is the
same as the response at any other location (except for boundaries).
By measuring a known conventional capacitor with the same
instrument, the voltage reading is converted to effective
capacitance readings.
[0134] The mutual no-touch capacitance for the inventive example
was 1.8 times higher than the comparative example at either 100 kHz
or 1 MHz. This increase illustrates the effective field-spreading
characteristic of the unpatterned conductive layer 30 in the
inventive example at practical measurement frequencies and is
usable to reduce the relative power consumption of a touch-sensor
controller resulting in improved system efficiency.
[0135] To test touch sensitivity, the examples were scanned with a
10.4 mm diameter artificial finger in a matrix pattern centered at
an intersection of the active second and first micro-wire
electrodes 52, 22. In each case, far from the intersection, the
capacitance was equivalent to the no-touch condition, as expected.
Centered on the intersection the capacitance was less than the
no-touch condition and the relative difference between the near
node touch and no-touch reading was taken as a measure of the touch
sensitivity.
Touch-Sensitivity=-(C.sub.touch-C.sub.no.sub.--.sub.touch)/C.sub.no.sub.-
--.sub.touch
[0136] At 1 MHz the relative touch sensitivity was 42% for the
inventive example and 50% for the comparative example. Thus, the
touch signal in the inventive example was strong and differences
between the inventive and comparative example small, demonstrating
that the unpatterned conductive layer 30 has minimal effect on the
touch sensitivity while increasing the capacitance. The observed
difference in touch sensitivity can be due in part or entirely to
imperfections of the alignment of driver and sensor electrodes
(first and second micro-wire electrodes 22, 52) in each
example.
[0137] To test the shielding properties, connections to the second
and first micro-wire electrodes 52, 22 were exchanged thus
reversing the roles of the first and second micro-wire electrodes
22, 52 and the artificial finger was scanned over the back-side of
the examples. By symmetry this makes no difference for the
comparative example but shows a reduction in touch sensitivity due
to the shielding effects of the field-spreading unpatterned
conductive layer 30 in the inventive example. Indeed, the results
showed a factor of 3 reductions in touch sensitivity at 1 MHz and
complete elimination of touch signal at 100 kHz for the inventive
example. This reduction in frequency response is an illustration of
the time constant for charging or discharging the open areas of the
unpatterned conductive layer 30 in the first micro-wire electrode
22. Touch sensitivity of the comparative example was unaffected, as
expected. Thus the field spreading unpatterned conductive layer 30
in the inventive example exhibited highly effective shielding at
practical frequencies with no deleterious effects due to electrical
shorting between first micro-wire electrodes 22. Capacitance signal
increased and little change in touch sensitivity was observed when
driven and sensed in the intended configuration achieving a
considerable improvement in overall system efficiency relative to
the prior art example was demonstrated.
[0138] 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 are 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.
[0139] In addition to the inventive and comparative examples
described, a touch-screen structure of the present invention having
a PEDOT/PSS unpatterned conductive layer 30 was constructed using
the imprinting techniques described and, in a separate sample, an
unpatterned conductive layer 30 of AZO on etched first micro-wires
24 was formed using atomic-layer deposition methods.
[0140] The first or second micro-wire electrodes 22, 52 can be
formed in a variety of patterns. Electrodes can be rectangular and
arranged in regular arrays. The first micro-wire electrodes 22 and
the second micro-wire electrodes 52 can be arranged orthogonally to
each other. Alternatively, electrodes can be arranged using polar
coordinates, in circles, or in other curvilinear patterns.
Electrodes can have uniform spacing or widths. Alternatively,
electrodes can have non-uniform spacing and variable widths.
[0141] 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.
[0142] 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
[0143] P direction [0144] D1 direction [0145] D2 direction [0146] 5
micro-wire electrode structure [0147] 10 substrate [0148] 11 touch
surface [0149] 12 surface [0150] 20 first layer [0151] 22 first
micro-wire electrode [0152] 24 first micro-wire [0153] 26 first gap
micro-wires [0154] 30 unpatterned conductive layer [0155] 32
touch-sensitive area [0156] 36 dummy-wire area [0157] 40 dielectric
layer [0158] 50 second layer [0159] 52 second micro-wire electrode
[0160] 54 second micro-wire [0161] 56 second gap micro-wires [0162]
60 first electrode gap [0163] 62 second electrode gap [0164] 64
micro-wire breaks [0165] 70 overcoat layer [0166] 80 gap layer
[0167] 100 display and touch-screen apparatus [0168] 110 display
[0169] 120 touch screen [0170] 122 first transparent substrate
[0171] 124 dielectric layer [0172] 126 second transparent substrate
[0173] 128 touch pad area
PARTS LIST (CON'T)
[0173] [0174] 130 first electrode [0175] 132 second electrode
[0176] 134 wires [0177] 136 electrical bus connections [0178] 140
touch-screen controller [0179] 142 display controller [0180] 150
micro-wire [0181] 152 dummy micro-wires [0182] 156 micro-pattern
[0183] 200 provide substrate surface step [0184] 205 provide first
layer step [0185] 210 locate first micro-wires step [0186] 215
provide second layer step [0187] 220 locate second micro-wires step
[0188] 225 provide gap layer step [0189] 230 locate gap micro-wires
step [0190] 250 locate second micro-wires and first gap micro-wires
step [0191] 260 provide unpatterned conductive layer step [0192]
270 locate dielectric layer step [0193] 280 locate first
micro-wires and second gap micro-wires step
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