U.S. patent application number 14/167175 was filed with the patent office on 2015-07-30 for micro-wire electrodes with dummy micro-dots.
The applicant listed for this patent is Ronald Steven Cok, William Yurich Fowlkes. Invention is credited to Ronald Steven Cok, William Yurich Fowlkes.
Application Number | 20150212613 14/167175 |
Document ID | / |
Family ID | 51626589 |
Filed Date | 2015-07-30 |
United States Patent
Application |
20150212613 |
Kind Code |
A1 |
Fowlkes; William Yurich ; et
al. |
July 30, 2015 |
MICRO-WIRE ELECTRODES WITH DUMMY MICRO-DOTS
Abstract
A micro-wire multi-electrode structure having an area of
substantially uniform optical density includes a plurality of
spatially separated patterned electrodes in an electrode layer in
the area. Each electrode includes a plurality of patterned
conductive electrically connected electrode micro-wires. A
plurality of patterned electrically isolated dummy micro-dots are
located between adjacent electrodes and arranged to provide a
substantially uniform optical density in the area. An unpatterned
conductive layer is located in the area in electrical contact with
the electrode micro-wires and dummy micro-dots.
Inventors: |
Fowlkes; William Yurich;
(Pittsford, NY) ; Cok; Ronald Steven; (Rochester,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fowlkes; William Yurich
Cok; Ronald Steven |
Pittsford
Rochester |
NY
NY |
US
US |
|
|
Family ID: |
51626589 |
Appl. No.: |
14/167175 |
Filed: |
January 29, 2014 |
Current U.S.
Class: |
345/173 ;
174/253; 29/825 |
Current CPC
Class: |
H05K 1/0216 20130101;
G06F 2203/04107 20130101; H05K 1/0296 20130101; Y10T 29/49105
20150115; G06F 3/042 20130101; G06F 3/046 20130101; G06F 3/04164
20190501; G06F 1/16 20130101; Y10T 29/49117 20150115; G06F
2203/04111 20130101; G06F 3/0412 20130101; H05K 2201/10204
20130101; G06F 2203/04112 20130101; G06F 3/0445 20190501; G06F
3/0446 20190501; G06F 3/047 20130101; G06F 2203/04103 20130101 |
International
Class: |
G06F 3/042 20060101
G06F003/042; G06F 3/041 20060101 G06F003/041; H05K 1/02 20060101
H05K001/02 |
Claims
1. A micro-wire multi-electrode structure having an area of
substantially uniform optical density, comprising: a plurality of
spatially separated patterned electrodes in an electrode layer in
the area, each electrode including a plurality of patterned
conductive electrically connected electrode micro-wires; a
plurality of patterned electrically isolated dummy micro-dots
between adjacent electrodes, arranged to provide a substantially
uniform optical density in the area; and an unpatterned conductive
layer in the area, the unpatterned conductive layer in electrical
contact with the electrode micro-wires and dummy micro-dots.
2. The micro-wire multi-electrode structure of claim 1, wherein the
dummy micro-dots have a circular cross section.
3. The micro-wire multi-electrode structure of claim 1, wherein the
dummy micro-dots have a square or polygonal cross section.
4. The micro-wire multi-electrode structure of claim 1, wherein the
dummy micro-dots are located in a plurality of lines in the area
between adjacent electrodes.
5. The micro-wire multi-electrode structure of claim 4, wherein the
electrodes extend in a direction and the lines in which the dummy
micro-dots are located extend in the same direction.
6. The micro-wire multi-electrode structure of claim 4, wherein at
least some of the electrode micro-wires extend in a direction and
the lines in which the dummy micro-dots are located extend in the
same direction.
7. The micro-wire multi-electrode structure of claim 1, wherein the
electrode micro-wires form a pattern and the dummy micro-dots form
a similar pattern in the area between adjacent electrodes.
8. The micro-wire multi-electrode structure of claim 1, wherein the
dummy micro-dots are located randomly or pseudo-randomly in the
area between adjacent electrodes.
9. The micro-wire multi-electrode structure of claim 1, wherein the
electrodes are drive electrodes, the electrode layer is a drive
layer, the electrode micro-wires are drive micro-wires, and the
area is a touch-sensitive area and further including: a sense layer
separate from the drive layer; a dielectric layer located between
the drive layer and the sense layer; and a plurality of spatially
separated patterned sense electrodes in the sense layer in the
area, each sense electrode including a plurality of patterned
conductive electrically connected sense micro-wires.
10. The micro-wire multi-electrode structure of claim 9, wherein
the dummy micro-dots are located in the drive layer.
11. The micro-wire multi-electrode structure of claim 9, further
including additional dummy micro-dots located in the sense
layer.
12. The micro-wire multi-electrode structure of claim 1, wherein
the dummy micro-dots are located in the electrode layer.
13. The micro-wire multi-electrode structure of claim 1, wherein
the dummy micro-dots and the electrode micro-wires are the same
material.
14. The micro-wire multi-electrode structure of claim 1, wherein
the area defines an edge and further including an edge electrode
adjacent to the edge and edge dummy micro-dots located between the
edge electrode and the edge of the area.
15. The micro-wire multi-electrode structure of claim 14, further
including an electrical wire electrically connected to electrodes
and located adjacent to the edge of the area and outside the area
and the edge dummy micro-dots are located between the electrodes
and the electrical wire.
16. The micro-wire multi-electrode structure of claim 1, wherein
first dummy micro-dots are located between first adjacent
electrodes in a first pattern and second dummy micro-dots are
located between second adjacent electrodes in a second pattern
different from the first pattern or that is the same as the first
pattern.
17. The micro-wire multi-electrode structure of claim 1, wherein
the plurality of spatially separated patterned electrodes in the
area form a regular array of electrodes.
18. A touch-screen device having a touch-sensitive area of
substantially uniform optical density, comprising: a plurality of
spatially separated patterned drive electrodes in a drive layer in
the touch-sensitive area, each drive electrode including a
plurality of patterned conductive electrically connected drive
micro-wires; a plurality of spatially separated patterned sense
electrodes in a sense layer in the touch-sensitive area, each sense
electrode including a plurality of patterned conductive
electrically connected sense micro-wires; a dielectric layer
located between the drive electrodes and the sense electrodes; one
or more patterned electrically isolated dummy micro-dots randomly
arranged in the touch-sensitive area located in drive layer between
adjacent drive electrodes, and electrically disconnected from the
adjacent drive electrodes, whereby the touch-sensitive area has a
substantially uniform optical density; a conductive layer that is
unpatterned in the touch-sensitive area, the conductive layer in
electrical contact with the drive micro-wires and dummy micro-dots;
and a controller electrically connected to the drive and sense
electrodes for controlling the drive and sense electrodes.
19. A method of making a micro-wire multi-electrode structure
having an area of substantially uniform optical density,
comprising: providing a plurality of spatially separated patterned
electrodes in an electrode layer in the area, each electrode
including a plurality of patterned conductive electrically
connected electrode micro-wires; locating one or more patterned
electrically isolated dummy micro-dots in the area, whereby the
area has a substantially uniform optical density; and locating an
unpatterned conductive layer in the area, the unpatterned
conductive layer in electrical contact with the electrode
micro-wires and dummy micro-dots.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to commonly-assigned, co-pending U.S.
patent application Ser. No. ______ filed concurrently herewith,
entitled "Micro-Wire Electrodes with Equi-Potential Dummy
Micro-Wires" by Cok and 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, the disclosures of which are incorporated
herein.
FIELD OF THE INVENTION
[0002] The present invention relates to touch screens having
micro-wire electrodes, an unpatterned transparent conductor layer,
and electrically isolated dummy structures.
BACKGROUND OF THE INVENTION
[0003] Transparent conductors are widely used in the flat-panel
display industry to form electrodes that are used to electrically
switch light-emitting or light-transmitting properties of a display
pixel, for example in liquid crystal or organic light-emitting
diode displays. Transparent conductive electrodes are also used in
touch screens in conjunction with displays. In such applications,
the transparency and conductivity of the transparent electrodes are
important attributes. In general, it is desired that transparent
conductors have a high transparency (for example, greater than 90%
in the visible spectrum) and a low electrical resistivity (for
example, less than 10 ohms/square).
[0004] Transparent conductive metal oxides are well known in the
display and touch-screen industries and have a number of
disadvantages, including limited transparency and conductivity and
a tendency to crack under mechanical or environmental stress.
Typical prior-art conductive electrode materials include conductive
metal oxides such as indium tin oxide (ITO) or very thin layers of
metal, for example silver or aluminum or metal alloys including
silver or aluminum. These materials are coated, for example, by
sputtering or vapor deposition, and are patterned on display or
touch-screen substrates, such as glass. For example, the use of
transparent conductive oxides to form arrays of touch 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".
[0005] Transparent conductive metal oxides are increasingly
expensive and relatively costly to deposit and pattern. Moreover,
the substrate materials are limited by the electrode material
deposition process (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.
[0006] 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%.
[0007] Conductive micro-wires are formed in micro-channels embossed
in a substrate, for example as taught in CN102063951, which is
hereby incorporated by reference in its entirety. As discussed in
CN102063951, a pattern of micro-channels are formed in a substrate
using an embossing technique. Embossing methods are generally known
in the prior art and typically include coating a curable liquid,
such as a polymer, onto a rigid substrate. A pattern of
micro-channels is embossed (impressed 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.
[0008] 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. 31,
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 first
transparent electrodes 130 extending in the x dimension on the
first transparent substrate 122 and a second transparent substrate
126 with second transparent electrodes 132 extending in the y
dimension facing the x-dimension first transparent electrodes 130
on the second transparent substrate 126. A dielectric layer 124 is
located between the first and second transparent substrates 122,
126 and first and second transparent electrodes 130, 132. Touch pad
areas 128 are formed by the overlap of the first transparent
electrodes 130 and the second transparent electrodes 132. When a
voltage is applied across the first and second transparent
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.
[0009] A display controller 142 connected through electrical buss
connections 136 controls the display 110 in cooperation with a
touch-screen controller 140. The touch-screen controller 140 is
connected through electrical buss 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 x-dimension first and
y-dimension second transparent electrodes 130, 132.
[0010] Referring to FIG. 32 as well as FIG. 31, in another
prior-art embodiment, the rectangular first and second transparent
electrodes 130, 132 that include micro-wires 150 are arranged
orthogonally in a micro-pattern 156 on first and second transparent
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 apparatus 100.
[0011] 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 can be ameliorated 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.
[0012] Alternatively, it has been recognized that shielding can be
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 can be 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.
[0013] 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.
[0014] 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,
relatively 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 gaps between electrodes are visible as areas with increased
transparency.
[0015] To reduce the visibility of gaps between electrodes in a
touch screen, dummy structures are provided in the gaps. 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. Gaps between the dummy
structures and the electrodes are typically so small (for example,
a few microns) that the gaps are imperceptible to viewers.
Referring to FIG. 33, a plurality of rectangular, spatially
separated first transparent electrodes 130 are arranged in an array
on a first transparent substrate 122. Each first transparent
electrode 130 includes a plurality of electrically connected
micro-wires 150. Dummy micro-wires 152 located in gaps 60 between
the first transparent electrodes 150 are arranged in a similar way
so that the dummy micro-wires 152 located in the gaps 60 between
the first transparent electrodes 130 appear similar to the
micro-wire electrodes 130.
[0016] 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
[0017] There remains a need for further improvements in the
structure of a multi-electrode structure that reduces
susceptibility to electromagnetic interference, reduces thickness
and cost, improves sensitivity and efficiency, and provides optical
uniformity.
[0018] In accordance with the present invention, a micro-wire
multi-electrode structure having an area of substantially uniform
optical density comprises: [0019] a plurality of spatially
separated patterned electrodes in an electrode layer in the area,
each electrode including a plurality of patterned conductive
electrically connected electrode micro-wires; [0020] a plurality of
patterned electrically isolated dummy micro-dots between adjacent
electrodes, arranged to provide a substantially uniform optical
density in the area; and [0021] an unpatterned conductive layer in
the area, the unpatterned conductive layer in electrical contact
with the electrode micro-wires and dummy micro-dots.
[0022] The present invention provides a micro-wire multi-electrode
structure useful in capacitive touch screens having improved
sensitivity, efficiency, consistency, optical uniformity, and
reduced susceptibility to electromagnetic interference and reduced
thickness and cost. The presence of an unpatterned conductive layer
electrically connected to drive electrodes and drive micro-wires
provides electromagnetic shielding to sense electrodes, thereby
reducing electromagnetic interference. The integrated unpatterned
conductive layer reduces device thickness by reducing the number of
insulating layers, reducing conductive layer thickness, and
improving transparency in comparison to a conventional shielding
system. The presence of dummy structures improves optical
uniformity without compromising the function of the unpatterned
conductive layer.
[0023] The presence of the unpatterned conductive layer also
increases capacitance between drive and sense electrodes, thereby
reducing the voltage needed to sense changes in the capacitive
field, for example due to touches, and improving efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] 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:
[0025] FIG. 1A is a plan view of an embodiment of the present
invention;
[0026] FIG. 1B is a cross section of the embodiment of FIG. 1A
taken along cross section line B of FIG. 1A;
[0027] FIG. 1C is a cross section of the embodiment of FIG. 1A
taken along cross section line C of FIG. 1A;
[0028] FIG. 2A is a plan view of a micro-structure useful in
understanding the present invention;
[0029] FIG. 2B is a plan view of an alternative micro-structure
useful in understanding the present invention;
[0030] FIG. 3 is a plan view of another micro-structure useful in
understanding the present invention;
[0031] FIG. 4 is a plan view of another embodiment of the present
invention;
[0032] FIG. 5 is a plan view of yet another embodiment of the
present invention;
[0033] FIG. 6 is a flow chart illustrating a method of the present
invention;
[0034] FIG. 7A is a plan view of an embodiment of the present
invention;
[0035] FIG. 7B is a cross section of the embodiment of FIG. 7A
taken along cross section line B of FIG. 7A;
[0036] FIG. 7C is a cross section of the embodiment of FIG. 7A
taken along cross section line C of FIG. 7A;
[0037] FIGS. 8-12 are plan views of various micro-structures useful
in understanding the present invention;
[0038] FIG. 13 is a plan view of an embodiment of the present
invention;
[0039] FIG. 14 is a plan view of another embodiment of the present
invention;
[0040] FIGS. 15-26 are cross sections of various embodiments of the
present invention;
[0041] FIG. 27 is a perspective of another embodiment of the
present invention;
[0042] FIG. 28 is a plan view of a micro-wire structure useful in
an embodiment of the present invention;
[0043] FIG. 29 is a flow diagram illustrating the construction of
an embodiment of the present invention;
[0044] FIG. 30 is a cross section of an experimental sample of an
embodiment of the present invention;
[0045] FIG. 31 is a perspective of a touch screen and display
apparatus according to the prior art;
[0046] FIG. 32 is a plan view of micro-wire electrodes according to
the prior art; and
[0047] FIG. 33 is a plan view of micro-wire electrodes and dummy
micro-wires according to the prior art.
[0048] 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
[0049] The present invention provides a micro-wire multi-electrode
structure useful, for example, in touch-screen devices in
combination with a display. The micro-wire multi-electrode
structure reduces the effects of electromagnetic interference and
improves touch-response sensitivity, efficiency, consistency, and
optical uniformity over the extent of the touch screen.
[0050] Referring to FIG. 1A in a plan view and to FIGS. 1B and 1C
in cross sections taken along cross section lines B and C,
respectively, of FIG. 1A, an embodiment of a micro-wire
multi-electrode structure 5 of the present invention has an area 31
of substantially uniform optical density that includes a plurality
of spatially separated patterned electrodes 22 located in an
electrode layer 20 in the area 31. Each electrode 22 includes a
plurality of patterned conductive and electrically connected
electrode micro-wires 24. The electrodes 22 are spatially separated
by gaps 26. One or more patterned electrically conductive
equi-potential dummy micro-wires 90 are located in the area 31
substantially along equi-potential lines between adjacent
electrodes 22, for example in the gaps 26. Adjacent electrodes 22
are pairs of electrodes 22 between which there is no other
electrode 22. The dummy micro-wires 90 are electrically isolated
from the electrode micro-wires 24. An unpatterned conductive layer
30 in the area 31 is in electrical contact with the electrode
micro-wires 24 and the dummy micro-wires 90. The percent of
incident light transmitted through the gap 26 and the dummy
micro-wires 90 is similar to the percent of incident light
transmitted through the electrodes 22 and the electrode micro-wires
24, so that the area 31 has a substantially uniform optical
density.
[0051] The area of the unpatterned conductive layer 30 is equal to
or greater than the area 31 of uniform optical density and the
unpatterned conductive layer 30 is not necessarily distinguished
from the area 31 in the Figures. Generally, the unpatterned
conductive layer 30 is illustrated in cross sections and the area
31 is indicated in the plan views.
[0052] The unpatterned conductive layer 30 in the area 31 can refer
to the touch-sensitive portion of a layer of conductive material
located over a substrate 10. The unpatterned conductive layer 30 is
a layer of electrically conductive material that can extend beyond
the area 31 and can be patterned outside of the area 31, for
example around the periphery of a touch screen (such as in the
bezel or buss areas of a touch screen), but is unpatterned within
the area 31. The electrodes 22 can extend beyond the area 31 or the
unpatterned conductive layer 30.
[0053] In an embodiment, the electrode micro-wires 24 form a mesh
and typically have a width less than 10 microns and a pitch of
hundreds or even more than a thousand microns. Since such relative
sizes and spacing are difficult to illustrate in the Figures, the
micro-structures (such as the electrode micro-wires 24) are
typically shown much larger and closer together than is the case in
a practical implementation. In an embodiment of the present
invention, the micro-structures of the present invention, including
the electrode micro-wires 24 and dummy micro-wires 90 are too small
to be resolved by, or visible to, the unaided human visual
system.
[0054] Optical uniformity, as used herein refers to optical
uniformity as easily perceived by the unaided human visual system
without special effort under typical display viewing conditions and
is averaged over areas much larger than the individual
micro-structures in the optically uniform area 31, for example
areas of several square millimeters. Substantially uniform means
that the area 31 appears uniform to the unaided human visual
system. The area 31 can have less than 20%, 10%, 5%, 2%, or 1%
variation over the area 31. The spatial distribution of the
electrode micro-wires 22 and dummy micro-wires 90 in the area 31
can affect the optical uniformity of the area 31 so that, in an
embodiment of the present invention, the area 31 has a
substantially uniform spatial distribution of electrode micro-wires
22 and dummy micro-wires 90 in the area 31.
[0055] Although the present invention discloses an optically
uniform area 31, such uniformity is not readily illustrated in the
Figures and the optically uniform area 31 in the Figures is not
necessarily illustrated as optically uniform. Furthermore, optical
uniformity is taken over a two-dimensional area. Cross-sectional
Figures represent only one dimension of the area 31 and are not,
therefore, illustrative of optical uniformity.
[0056] The electrode micro-wires 24 are electrically connected
within each electrode 22 but are not electrically connected to
electrode micro-wires 24 of other electrodes 22. Thus, each
electrode 22 is electrically isolated from any other electrode 22.
Furthermore, the dummy micro-wires 90 are not electrically
connected to any electrode micro-wires 24. In an embodiment, the
dummy micro-wires 90 are formed in a common layer with the
electrode micro-wires 24 or include one or more common materials
with the electrode micro-wires 24. In another embodiment, the dummy
micro-wires 90 and the electrode micro-wires 24 are formed from the
same materials. In an embodiment, the dummy micro-wires 90 and the
electrode micro-wires 24 are formed in a common step with common
materials in a common layer and have a common thickness. In another
embodiment, the dummy micro-wires 90 have a thickness that is less
than the thickness of the electrode micro-wires 24.
[0057] Each dummy micro-wire 90 extends along an equi-potential
line. When adjacent electrodes 22 are energized at different
voltages, an electrical field exists between the electrodes 22. For
example, two opposing, parallel conductors will create an
electrical field having field lines that extend orthogonally from
one conductor to the other (ignoring edge effects). Each point
along each field line has an electrical potential. The dummy
micro-wires 90 extend from field line to field line at positions of
equal electrical potential. In the case of two opposing, parallel
conductors and orthogonal field lines, the equi-potential lines
will be lines parallel to the conductors. Thus, an equi-potential
line is a set of connected points forming at least a portion of a
line, curved or straight, that have a common potential when the
micro-wires 24 of adjacent electrodes 22 are controlled to have
different voltage potentials. Each dummy micro-wire 90 extends
along an equi-potential line. Different dummy micro-wires 90 can
extend along different equi-potential lines so that the different
dummy micro-wires 90 can have different electrical potentials.
Moreover, the dummy micro-wires 90 can extend over only a portion
of an equi-potential line. Multiple, electrically isolated dummy
micro-wires 90 can extend along a common, same equi-potential line
(for example as a sequence of dashed lines). Electrically isolated
dummy micro-wires 90 are micro-wires that are not electrically
connected to any electrode micro-wires 24.
[0058] By substantially equi-potential is meant that the
conductivity of the unpatterned conductive layer 30 is not changed
so much that the electrodes 22 cannot effectively maintain
different voltages when driven by a drive circuit or that the
conductivity of the unpatterned conductive layer 30 is not changed
so much that electrical fields generated by the electrodes 22
cannot be distinguished with a sense circuit (e.g. drive and sense
circuits in touch-screen controller 140). Thus, the dummy
micro-wires 90 provide optical density in the gap 26 without
compromising the conductivity of the unpatterned conductive layer
30 by increasing the conductivity to an unacceptable level.
[0059] In a further embodiment of a micro-wire multi-electrode
structure 5, the electrodes 22 are drive electrodes 22, the
electrode layer 20 is a drive layer 20, the electrode micro-wires
24 are drive micro-wires 24, gaps 26 separating the drive
electrodes 22 are drive gaps 26, and the area 31 is a
touch-sensitive area 31.
[0060] In this embodiment, a plurality of spatially separated
patterned sense electrodes 52 is located in a sense layer 50 in the
touch-sensitive area 31. Each sense electrode 52 includes a
plurality of patterned conductive electrically connected sense
micro-wires 54. The sense electrodes 52 are separated by sense gaps
56 and a dielectric layer 40 is located between the drive
electrodes 22 and the sense electrodes 52. Areas in which the drive
electrodes 22 and the sense electrodes 52 overlap form touch-pad
areas 128. The touch-pad areas 128 form capacitors whose
capacitance changes can be measured to detect a touch.
[0061] In one embodiment, the dielectric layer 40 is a separate
layer (e.g. as shown in FIG. 31 with dielectric layer 124), in
another embodiment the dielectric layer 40 is a portion of another
layer, for example a portion of the sense layer 50 as shown in
FIGS. 1B and 1C. In an embodiment, a protective overcoat layer 70
is provided over the sense layer 50. A surface of the protective
overcoat layer 70 provides a touch surface 11.
[0062] FIG. 1B is taken along the cross section line B of FIG. 1A
where the drive micro-wires 24 overlap the sense micro-wires 54. To
aid understanding, FIG. 1C is also provided to clarify an
embodiment of the present invention. FIG. 1C is taken along the
cross section line C of FIG. 1A where the drive micro-wires 24
overlap the drive micro-wires 24 and the sense micro-wires 54
overlap the drive micro-wires 54.
[0063] Although illustrated in FIGS. 1B and 1C with the drive layer
20 between the sense layer 50 and the substrate 10, in another
embodiment, as discussed below, the sense layer 50 is located
between the drive layer 20 and the substrate 10, or the sense layer
50 and the drive layer 20 are located on opposite sides of the
substrate 10. In an embodiment of the present invention, and as
illustrated in FIGS. 1B and 1C, the dummy micro-wires 90 are
located in the drive layer 20.
[0064] Referring to FIG. 2A, in an embodiment a first dummy
micro-wire 90A is located along a first equi-potential line and a
second dummy micro-wire 90B is located along a second
equi-potential line different from the first equi-potential line
between electrodes 22 with electrode micro-wires 24. Referring to
FIG. 2B, in other embodiments, separate multiple dummy micro-wires
90A are located along portions of a common equi-potential line or
have a different pattern from other dummy micro-wires 90B. The
dummy micro-wires 90 can form straight lines or straight line
segments. The straight line segments can be connected at an angle
(not shown).
[0065] Referring to FIG. 3, adjacent electrodes 22 having electrode
micro-wires 24 are separated by the dummy micro-wires 90A in gap
26A. The dummy micro-wires 90A are curved and dummy micro-wires 90A
at different equi-potentials have different shapes. The dummy
micro-wires 90B in gap 26B between adjacent electrodes 22 have a
different shape or pattern from the dummy micro-wires in gap 26A.
Thus, in various embodiments of the present invention, the dummy
micro-wires have different shapes or patterns within a gap or in
different gaps so that first dummy micro-wires 90A are located
between first adjacent electrodes 22 in a first pattern and second
dummy micro-wires 90B are located between second adjacent
electrodes 22 in a second pattern different from the first pattern.
Alternatively, as shown in FIG. 1A, first dummy micro-wires 90 are
located between first adjacent electrodes 22 in a first pattern and
second dummy micro-wires 90 are located between second adjacent
electrodes 22 in a second pattern that is the same as the first
pattern.
[0066] Furthermore, the patterns of electrode micro-wires 24 can
vary. Referring to FIG. 3, the plurality of spatially separated
patterned electrodes 22 in the area 31 can include a first
electrode 22 having electrically connected electrode micro-wires 24
forming a first pattern and a second electrode 22 having
electrically connected electrode micro-wires 24 forming a second
pattern different from the first pattern. As shown in FIG. 3, the
center and left electrodes 22 are mirror images and the center and
right electrodes 22 are different mirror images. Alternatively, the
first and second electrode micro-wire patterns are the same pattern
(e.g. as in FIG. 1A). In some embodiments, the plurality of
spatially separated patterned electrodes 22 in the area 31 forms a
regular array of electrodes 22.
[0067] Referring to FIG. 4 and also to FIGS. 1A and 1B, in a
further embodiment of a micro-wire multi-electrode structure 5,
additional dummy micro-wires 94 are provided. The additional dummy
micro-wires 94 provide optical uniformity in the sense gaps 56
between sense electrodes 52 having sense micro-wires 54. The
additional dummy micro-wires 94 complement the dummy micro-wires 90
in the drive gaps 26 between drive electrodes 22 having drive
micro-wires 24. The additional dummy micro-wires 94 are not
necessarily electrically connected to the unpatterned conductive
layer 30 in the area 31, are therefore not necessarily located
along equi-potential lines between the sense electrodes 52 and, in
an embodiment, are located in the sense layer 50.
[0068] Referring next to FIG. 5, an embodiment of a micro-wire
multi-electrode structure 5 includes a plurality of electrodes 22
having electrode micro-wires 24 formed in or on the substrate 10 in
the area 31. The electrodes 22 are separated by gaps 26 having
dummy micro-wires 90 arranged along equi-potential lines. The area
31 has an area edge 33 and includes an edge electrode 23 adjacent
to the area edge 33. By adjacent is meant that no other electrode
22 is between the area edge 33 and the edge electrode 23. Edge
dummy micro-wires 96 are located along equi-potential lines between
the edge electrode 23 and the area edge 33 and are electrically
disconnected from the edge electrode 23. Thus optical uniformity is
preserved within the area 31 even if the edge electrode 23 is not
at the area edge 33. In a further embodiment, an electrical wire
134 is located outside the area 31 and adjacent to the area edge
33. Edge dummy micro-wires 96 are located between the edge
electrode 23 and the electrical wire 134. Electrical wires 134 are
combined to form electrical busses 136. FIG. 5 only illustrates the
drive electrodes 22 in the drive layer 20 and not the sense
electrodes 52 in the sense layer 50. In an embodiment, the
electrical wire 134 located outside the area 31 and adjacent to the
area edge 33 is electrically connected to a sense electrode 52. In
an embodiment, the electrical wire 134 is in the drive layer 20
(not shown in FIG. 5); in another embodiment the electrical wire
134 is in the sense layer 50 (not shown in FIG. 5).
[0069] In an embodiment of the present invention, a touch-screen
device having a substantially uniform optical density in a
touch-sensitive area 31 includes a plurality of spatially separated
patterned drive electrodes 22 located in a drive layer 20 in the
touch-sensitive area 31. Each drive electrode 22 includes a
plurality of patterned conductive electrically connected drive
micro-wires 24. A plurality of spatially separated patterned sense
electrodes 52 in the sense layer 50 is located in the
touch-sensitive area 31. Each sense electrode 52 includes a
plurality of patterned conductive electrically connected sense
micro-wires 54. A dielectric layer 40 is located between the drive
electrodes 22 and the sense electrodes 52. One or more patterned
electrically isolated equi-potential dummy micro-wires 90 are
located in the touch-sensitive area 31 substantially along
equi-potential lines between adjacent drive electrodes 22 and
electrically disconnected from the adjacent drive electrodes 22, so
that the touch-sensitive area 31 has a substantially uniform
optical density. An unpatterned conductive layer 30 that is
unpatterned in the touch-sensitive area 31 is in electrical contact
with the drive micro-wires 24 and the dummy micro-wires 90. A
controller is electrically connected to the drive and sense
electrodes 22, 52 to control the drive and sense electrodes 22,
52.
[0070] Referring to the flow-diagram of FIG. 6, a method of making
a micro-wire multi-electrode structure 5 having an area 31 of
substantially uniform optical density includes providing in step
500 a plurality of spatially separated patterned electrodes 22 in
an electrode layer 20 in the area 31. Each electrode 22 includes a
plurality of patterned conductive electrically connected electrode
micro-wires 24. One or more patterned electrically isolated dummy
micro-structures are located in step 505 in the area 31. In this
embodiment, the micro-structures include electrode micro-wires 24
and dummy micro-wires 90 located substantially along equi-potential
lines between adjacent electrodes 22, so that the area 31 has a
substantially uniform optical density. In step 510, an unpatterned
conductive layer 30 is located in step 515 in the area 31. The
unpatterned conductive layer 30 is in electrical contact with the
electrode micro-wires 24 and dummy micro-wires 90.
[0071] Referring to FIG. 7A, in an alternative embodiment of the
present invention, dummy micro-dots 92 are used in place of dummy
micro-wires 90. The dummy micro-dots 92 are micro-structures that
have negligible conductivity in any given direction, for example
having a cross section in the plane of the electrode layer 20 that
is a circle, a square, or other polygonal shape that has an
effective aspect ratio of one. The dummy micro-dots 92 can have a
thickness (depth) that is similar to a thickness (depth) of the
electrode micro-wires 24. Alternatively, the dummy micro-dots 92
can have a thickness that is less than the thickness of the
electrode micro-wires 22. In either case, for example, dummy
micro-dots 92 that have a circular cross section are
cylindrical.
[0072] Although the dummy micro-dots 92 have a negligible
conductivity in any given direction, they do absorb or reflect
light and can therefore provide a substantially uniform optical
density in the area 31. A negligible conductivity in any given
direction is a conductivity that is small enough that conductivity
of the unpatterned conductive layer 30 is not changed so much that
the electrodes 22 cannot effectively maintain different voltages
when driven by a drive circuit or that the conductivity of the
unpatterned conductive layer 30 is not changed so much that
electrical fields generated by the electrodes 22 cannot be
distinguished with a sense circuit (e.g. drive and sense circuits
in touch-screen controller 140). Thus, the dummy micro-dots 92
provide optical density in the gap 26 without compromising the
conductivity of the unpatterned conductive layer 30 by increasing
the conductivity to an unacceptable level.
[0073] As shown in FIG. 7A in a plan view and in FIGS. 7B and 7C in
cross sections taken along cross section lines B and C,
respectively, of FIG. 7A, an embodiment of a micro-wire
multi-electrode structure 5 of the present invention has an area 31
of substantially uniform optical density that includes a plurality
of spatially separated patterned electrodes 22 located in an
electrode layer 20 in the area 31. Each electrode 22 includes a
plurality of patterned conductive and electrically connected
electrode micro-wires 24. The electrodes 22 are spatially separated
by gaps 26 and are arranged in a regular array. One or more
patterned dummy micro-dots 92 are located in the area 31, for
example in the gaps 26. Adjacent electrodes 22 are pairs of
electrodes 22 between which there is no other electrode 22. The
dummy micro-dots 92 are electrically isolated from the electrode
micro-wires 24. An unpatterned conductive layer 30 in the area 31
is in electrical contact with the electrode micro-wires 24 and the
dummy micro-dots 92. Light incident on the dummy micro-dots 92 is
absorbed or reflected in an amount similar to the amount of light
incident on the electrode micro-wires 24 that is absorbed or
reflected, so that the area 31 has a substantially uniform optical
density.
[0074] In various embodiments, the dummy micro-dots 92 are in a
common layer with the electrode 22 or electrode micro-wires 24, are
formed in a common step with the electrode micro-wires 24, include
similar materials or are made of the same materials as the
electrode micro-wires 24, or have a similar depth as the electrode
micro-wires 24.
[0075] In a further embodiment of a micro-wire multi-electrode
structure 5, the electrodes 22 are drive electrodes 22, the
electrode layer 20 is a drive layer 20, the electrode micro-wires
24 are drive micro-wires 24, gaps 26 separating the drive
electrodes 22 are drive gaps 26, and the area 31 is a
touch-sensitive area 31. In an embodiment, the dummy micro-dots 92
are in the same drive layer 20 as the drive micro-wires 24.
[0076] In this embodiment, a plurality of spatially separated
patterned sense electrodes 52 is located in the sense layer 50 in
the touch-sensitive area 31. Each sense electrode 52 includes a
plurality of patterned conductive electrically connected sense
micro-wires 54. The sense electrodes 52 are separated by sense gaps
56 and a dielectric layer 40 is located between the drive
electrodes 22 and the sense electrodes 52. Areas in which the drive
electrodes 22 and the sense electrodes 52 overlap form touch-pad
areas 128. The touch-pad areas 128 form capacitors whose
capacitance changes can be measured to detect a touch.
[0077] In one embodiment, the dielectric layer 40 is a separate
layer (e.g. as shown in FIG. 31 with dielectric layer 124), in
another embodiment the dielectric layer 40 is a portion of another
layer, for example a portion of the sense layer 50. In an
embodiment, the protective overcoat layer 70 is provided over the
sense layer 50. A surface of the protective overcoat layer 70
provides a touch surface 11.
[0078] FIG. 7B is taken along the cross section line B of FIG. 7A
where the sense micro-wires 54 overlap the drive micro-wires 24. To
aid understanding, FIG. 7C is also provided to clarify an
embodiment of the present invention. FIG. 7C is taken along the
cross section line C of FIG. 7A where the sense micro-wires 54 do
not overlap the drive micro-wires 24 but are offset from them along
the cross section.
[0079] Although illustrated in FIGS. 7B and 7C with the drive layer
20 between the sense layer 50 and the substrate 10, in another
embodiment, as discussed below, the sense layer 50 is located
between the drive layer 20 and the substrate 10, or the sense layer
50 and the drive layer 20 are located on opposite sides of the
substrate 10. In an embodiment of the present invention, and as
illustrated in FIGS. 7B and 7C, the dummy micro-dots 92 are located
in the drive layer 20.
[0080] In an embodiment, the dummy micro-dots 92 are arranged in
lines, arrays, or other regular arrangements. As shown in FIG. 7A,
the dummy micro-dots 92 are located in lines that extend in a
direction that is the same as the direction in which electrodes 22
extend. Referring to FIG. 8, the dummy micro-dots 92 located in the
gaps 26 are arranged in lines that extend in a direction that is
the same as the direction in which electrode micro-wires 24 in
electrodes 22 extend. In an embodiment, the dummy micro-dots 92 are
arranged in a regular array. Referring to FIG. 9, the dummy
micro-dots 92 are located randomly or pseudo-randomly in the gaps
26 between the electrode micro-wires 24 in electrodes 22.
[0081] Referring to FIG. 10, the electrode micro-wires 24 form a
pattern and the dummy micro-dots 92 form a similar pattern in the
gap 26 between adjacent electrodes 22, in this case a grid pattern.
As shown in FIG. 11, dummy micro-dots 92 in gap 26 between
electrodes 22 having electrode micro-wires 24 are arranged in lines
that extend in a direction of some of the electrode micro-wires 24
but not others.
[0082] Referring to FIG. 12, the arrangement of dummy micro-dots 92
in gaps 26 between electrodes 22 having electrode micro-wires 24
can be different between different pairs of adjacent electrodes in
different gaps 26. As shown in FIG. 12, the dummy micro-dots 92A in
gap 26A are arranged differently from the dummy micro-dots 92B in
gap 26B. Thus, in an embodiment, first dummy micro-dots 92A are
located between first adjacent electrodes in a first pattern and
second dummy micro-dots are located between second adjacent
electrodes in a second pattern different from the first pattern or
that is the same as the first pattern.
[0083] Drive or sense electrodes 22, 52 can be formed in a variety
of patterns. Electrodes can be rectangular and arranged in regular
arrays. Drive electrodes 22 and sense 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.
[0084] Referring to FIG. 13 and also to FIGS. 7B and 7C, a
micro-wire multi-electrode structure 5 further includes additional
dummy micro-dots 95 located in the sense layer 50. As shown in FIG.
13, dummy micro-dots 92 in gaps 26 between drive electrodes 22
having electrode micro-wires 24 provide optical uniformity in the
drive layer 20. Additional dummy micro-dots 95 in gaps 56 between
sense electrodes 52 having sense micro-wires 54 provide optical
uniformity in the sense layer 50 and over the area 31. In an
embodiment, additional dummy micro-wires 94 are provided in the
gaps 56 as shown in FIG. 4.
[0085] Referring next to FIG. 14, an embodiment of a micro-wire
multi-electrode structure 5 includes a plurality of electrodes 22
having electrode micro-wires 24 formed in or on the substrate 10 in
an area 31. The electrodes 22 are separated by gaps 26 having dummy
micro-dots 92 in the gaps 26. The area 31 has an area edge 33 and
includes an edge electrode 23 adjacent to the area edge 33. By
adjacent is meant that no other electrode is between the area edge
33 and the edge electrode 23. Edge dummy micro-dots 98 are located
between the area edge 33 and the edge electrode 23 and are
electrically disconnected from the edge electrode 23. Thus optical
uniformity is preserved within the area 31 even if the edge
electrode 23 is not at the area edge 33. In a further embodiment,
an electrical wire 134 is located outside the area 31 and adjacent
to the area edge 33. Edge dummy micro-dots 98 are located between
the edge electrode 23 and the electrical wire 134. Electrical wires
134 are combined to form electrical busses 136. FIG. 14 only
illustrates the drive electrodes 22 in the drive layer 20 and not
the sense electrodes 52 in the sense layer 50. In an embodiment,
the electrical wire 134 located outside the area 31 and adjacent to
the area edge 33 is electrically connected to the sense electrode
52. In an embodiment, the electrical wire 134 is in the drive layer
20 (not shown in FIG. 14); in another embodiment the electrical
wire 134 is in the sense layer 50 (not shown in FIG. 14).
[0086] In an embodiment of the present invention, a touch-screen
device having a substantially uniform optical density in a
touch-sensitive area 31 includes a plurality of spatially separated
patterned drive electrodes 22 located in a drive layer 20 in the
touch-sensitive area 31. Each drive electrode 22 includes a
plurality of patterned conductive electrically connected drive
micro-wires 24. A plurality of spatially separated patterned sense
electrodes 52 in the sense layer 50 is located in the
touch-sensitive area 31. Each sense electrode 52 includes a
plurality of patterned conductive electrically connected sense
micro-wires 54. The dielectric layer 40 is located between the
drive electrodes 22 and the sense electrodes 52. One or more
patterned electrically isolated dummy micro-dots 92 are located in
the touch-sensitive area 31 and electrically disconnected from the
adjacent drive electrodes 22, so that the touch-sensitive area 31
has a substantially uniform optical density. The unpatterned
conductive layer 30 that is unpatterned in the touch-sensitive area
31 is in electrical contact with the drive micro-wires 24 and the
dummy micro-wires 90. The touch screen controller 140 is
electrically connected to the drive and sense electrodes 22, 52 to
control the drive and sense electrodes 22, 52.
[0087] In a method of the present invention, referring again to
FIG. 6, a plurality of spatially separated patterned drive
electrodes 22 are provided in step 500 in a drive layer 20 in the
area 31, each drive electrode 22 including a plurality of patterned
conductive electrically connected drive micro-wires 24. One or more
patterned electrically isolated dummy micro-structures, in this
case micro-dots 92, are located in the area 31 in step 505, so that
the area 31 has a substantially uniform optical density. The
unpatterned conductive layer 30 is located in the area 31 in step
510 in electrical contact with the drive micro-wires 24 and dummy
micro-dots 92. In step 515, the dielectric layer 40 is located
adjacent to the drive electrodes 22 and in step 520, a plurality of
spatially separated patterned sense electrodes 52 are provided in
the sense layer 50 in the area 31, each sense electrode 52
including a plurality of patterned conductive electrically
connected sense micro-wires 54.
[0088] In various embodiments, the unpatterned conductive layer 30
is provided in various configurations with respect to the drive
layer 20, the sense layer 50 and the substrate 10. In these
embodiments, the dummy micro-wires 90 or dummy micro-dots 92 are
formed in the same layer as the drive micro-wires 24 and are not
shown separately.
[0089] Referring to FIG. 15, in cross section, to FIG. 27 in
perspective, and to FIG. 28 in plan view, in an embodiment of the
present invention the micro-wire multi-electrode structure 5
includes a plurality of patterned drive electrodes 22 in a
touch-sensitive area 31, each drive electrode 22 including the
plurality of patterned conductive electrically connected drive
micro-wires 24. An unpatterned conductive layer 30 that is
unpatterned in the touch-sensitive area 31 is in electrical contact
with the drive electrodes 22. A plurality of patterned sense
electrodes 52 in the touch-sensitive area 31, each sense electrode
52 including a plurality of patterned conductive electrically
connected sense micro-wires 54 is located on a side of the
dielectric layer 40 opposite the drive electrodes 22 so that the
dielectric layer 40 is located between the drive electrodes 22 and
the sense electrodes 52 and electrically insulates the drive
micro-wires 24 from the sense electrodes 52. An optional protective
overcoat layer 70 on the sense electrodes 52 protects the sense
electrodes 52 from the environment, and in particular from touches
by a finger or a stylus. FIG. 15 illustrates a cross section
through a single drive electrode 22 and along a single sense
micro-wire 54 of the sense electrode 52.
[0090] As is illustrated further in the embodiment of FIGS. 15 and
27, the drive electrodes 22, the unpatterned conductive layer 30,
the dielectric layer 40, and the sense electrodes 52 are formed on
the substrate 10 that can also serve as an element of the display
110, for example a display cover or substrate. Drive electrodes 22
are formed in the drive layer 20 and sense electrodes 52 are formed
in the sense layer 50. Such drive and sense layers 20, 50 can, for
example, include polymers such as curable polymers that are cured
in various ways, such as by exposure to ultra-violet radiation or
heat.
[0091] According to various embodiments of the present invention,
FIGS. 16-30 illustrate touch-screen devices having various
arrangements of the substrate 10, drive layer 20, unpatterned
conductive layer 30, dielectric layer 40, and sense layer 50.
Separate drive layers 20 or sense layers 50 are included in some
embodiments and not in other embodiments. Drive micro-wires 24,
dummy micro-wires 90, dummy micro-dots 92, and sense micro-wires 54
are formed in or on the various layers using a variety of
construction methods. The protective overcoat layer 70 can
optionally be provided on layers formed on either side of the
substrate 10.
[0092] In the embodiment of FIGS. 15, 20, and 23, the unpatterned
conductive layer 30 is between the drive electrodes 22 and the
dielectric layer 40. The drive micro-wires 24 are formed in the
separate drive layer 20. Referring to FIGS. 16, 18, 21, 22, 24, and
26 in an alternative arrangement according to various embodiments
of the present invention, the unpatterned conductive layer 30 is
not between the drive electrodes 22 and the dielectric layer 40 but
is rather on a side of the drive electrodes 22 opposite the
dielectric layer 40 or the sense electrodes 52 so that the drive
electrodes 22 are between the unpatterned conductive layer 30 and
the dielectric layer 40 or the sense electrodes 52. The drive
micro-wires 24, dummy micro-wires 90 (not shown), or dummy
micro-dots 92 (not shown) are formed in the dielectric layer 40. In
yet another embodiment illustrated in FIGS. 17 and 19, the drive
electrodes 22 are formed in the unpatterned conductive layer 30, so
that the unpatterned conductive layer 30 serves as the drive layer
20 supporting the drive electrodes 22. In all three sets of
arrangements, the sense micro-wires 54 are formed in the separate
sense layer 50.
[0093] In various embodiments of the present invention, the drive
electrodes 22 are adjacent to the substrate 10, as shown in FIGS.
15-20, 23, 25, and 27. By adjacent is meant that no other
electrodes are between the drive electrodes 22 and the substrate
10. The drive electrodes 22 are therefore located between the
substrate 10 and the dielectric layer 40. As illustrated in FIGS.
21, 24, and 26 in another embodiment, the sense electrodes 52 are
adjacent to the substrate 10 so that no other electrodes are
between the sense electrodes 52 and the substrate 10. The sense
electrodes 52 are therefore located between the substrate 10 and
the dielectric layer 40. In FIG. 24, the drive micro-wires 24 are
formed in the separate drive layer 20 and the sense micro-wires 54
are formed in a separate sense layer 50. The unpatterned conductive
layer 30 is located on a side of the drive electrodes 22 opposite
the dielectric layer 40. In FIG. 21, the drive micro-wires 24 are
formed in the dielectric layer 40 and the sense micro-wires 54 are
formed in the separate sense layer 50. The unpatterned conductive
layer 30 is located on the dielectric layer 40 on a side of the
dielectric layer 40 opposite the sense electrodes 52.
[0094] In an embodiment illustrated in FIG. 22, the drive
electrodes 22 and the sense electrodes 52 are on opposite sides of
the substrate 10 so that the substrate 10 also serves as the
dielectric layer 40. In this embodiment, as in the embodiment of
FIG. 24, the drive micro-wires 24, dummy micro-wires 90, or dummy
micro-dots 92 are formed in the separate drive layer 20 and the
sense micro-wires 54 are formed in the separate sense layer 50. The
unpatterned conductive layer 30 is located on a side of the drive
electrodes 22 opposite the dielectric layer 40 (substrate 10).
[0095] In the embodiment of FIG. 26, the drive micro-wires 24 and
dummy micro-wires 90 or dummy micro-dots 92 and the sense
micro-wires 54 are embedded in opposite sides of the dielectric
layer 40 formed on the substrate 10 adjacent to the sense
micro-wires 54. The unpatterned conductive layer 30 is on a side of
the drive micro-wires 24 opposite the dielectric layer 40.
[0096] Not all possible combinations and arrangements of layers are
illustrated herein. Other arrangements that provide patterned
micro-wire drive electrodes 22 electrically connected to an
unpatterned conductive layer 30 on a side of the dielectric layer
40 opposite patterned micro-wire sense electrodes 52 are included
within the present invention. In particular: either the drive
electrodes 22 or the sense electrodes 52 can be independently
arranged adjacent to the substrate 10; the unpatterned conductive
layer 30 is located between the drive electrodes 22 and the
dielectric layer 40, the drive electrodes 22 are located between
the conductive layer and the dielectric layer 40, or the drive
electrodes 22 are located at least partially in the unpatterned
conductive layer 30; the drive micro-wires 24, dummy micro-wires
90, or dummy micro-dots 92 are formed in the separate drive layer
20, in the dielectric layer 40, in the unpatterned conductive layer
30, or in the substrate 10; or the sense electrodes 52 are located
in a separate sense layer 50 or in the dielectric layer 40. Various
arrangements of each of these layers can be combined with other
layer arrangements. In general, the touch surface of the
touch-screen device is adjacent to the sense electrode 52. For
example, in FIGS. 21, 24, and 26 the touch surface 11 is a side of
the substrate 10. In the embodiments of FIGS. 15-20, the touch
surface 11 is opposite the substrate 10 rather than a substrate
side.
[0097] There are at least three methods of providing the drive
micro-wires 24, dummy micro-wires 90, dummy micro-dots 92, and
sense micro-wires 54. In one method, the drive layer 20 or sense
layer 50 is first formed and then the drive or sense micro-wires
24, 54, respectively, dummy micro-wires 90, or dummy micro-dots 92
are formed in micro-channels imprinted in the drive layer 20 or
sense layer 50 to embed the drive or sense micro-wires 24, 54,
dummy micro-wires 90, or dummy micro-dots 92 in the provided layer.
In the Figures, the drive or sense micro-wires 24, 54, dummy
micro-wires 90, or dummy micro-dots 92 are formed in micro-channels
and are illustrated as filling the micro-channels. Thus, the
micro-channels are not distinguished from the micro-wires in the
illustrations. In a second method, the drive or sense micro-wires
24, 54, dummy micro-wires 90, or dummy micro-dots 92 are first
formed, for example by printing or transfer onto the surface of
substrate 10, and then any subsequent drive layer 20 or sense layer
50 is coated, deposited, or otherwise provided over the drive or
sense micro-wires 24, 54, dummy micro-wires 90, or dummy micro-dots
92 to embed the drive or sense micro-wires 24, 54, dummy
micro-wires 90, or dummy micro-dots 92 in the provided layer. In a
third method, a pre-made layer (for example using either of the
first or second method) is laminated onto an underlying layer, for
example the surface of substrate 10. The pre-made layer can be, for
example, either of the sense layer 50 with sense micro-wires 54 or
the drive layer 20 with drive micro-wires 24, dummy micro-wires 90,
or dummy micro-dots 92.
[0098] As shown in FIGS. 15, 20, and 22-24, in the first method the
drive layer 20 is provided, for example as a curable drive layer 20
that is then imprinted with an imprinting stamp to form drive
micro-channels that are then filled with conductive ink and cured
to form the drive micro-wires 24, dummy micro-wires 90, or dummy
micro-dots 92 in the drive micro-channels in the drive layer 20. As
shown in FIG. 17, the unpatterned conductive layer 30, rather than
the separate drive layer 20, is imprinted with drive micro-channels
and having cured drive micro-wires 24. In the embodiment of FIG.
26, the drive micro-wires 24, dummy micro-wires 90, or dummy
micro-dots 92 are formed in imprinted drive micro-channels in the
dielectric layer 40. Similarly, the sense micro-wires 54 are formed
in sense micro-channels formed in the sense layer 50, as shown in
the embodiments of FIGS. 15-18, 21, 22, and 25. In FIG. 20, sense
micro-channels are imprinted in the dielectric layer 40 rather than
the separate sense layer 50 and sense micro-wires 54 are formed in
the sense micro-channels.
[0099] Referring to FIG. 25, drive micro-wires 24 can extend
through micro-channels formed in the drive layer 20 into the
unpatterned conductive layer 30 to electrically connect the drive
micro-wires 24, dummy micro-wires 90, or dummy micro-dots 92 to the
unpatterned conductive layer 30. In such an embodiment, the
unpatterned conductive layer 30 and the drive layer 20 can be
coated together, for example with slot or extrusion coating,
imprinted together with a stamp having protrusions as deep as or
deeper than the depth of drive layer 20. The drive and unpatterned
conductive layers 20, 30 are then cured together to form
micro-channels that are filled with conductive ink and cured to
form drive micro-wires 24, dummy micro-wires 90, or dummy
micro-dots 92 in the drive layer 20 in electrical contact with the
unpatterned conductive layer 30. The dielectric layer 40, sense
layer 50 with sense micro-wires 54, and protective overcoat layer
70 are formed as described with respect to FIG. 15.
[0100] In the second method of first forming micro-wires and then
coating over the micro-wires and as shown in the example of FIG.
16, the drive micro-wires 24, dummy micro-wires 90, or dummy
micro-dots 92 are printed or otherwise transferred on the
unpatterned conductive layer 30 and then the dielectric layer 40 is
provided, for example by coating or laminating, over the drive
micro-wires 24. In FIG. 18, the drive micro-wires 24 are printed or
otherwise transferred on the unpatterned conductive layer 30 and
then the drive layer 20 is provided, for example by coating, on the
drive micro-wires 24, dummy micro-wires 90, or dummy micro-dots 92.
In FIG. 19, the drive micro-wires 24, dummy micro-wires 90, or
dummy micro-dots 92 are printed or otherwise transferred on the
substrate 10 and then the unpatterned conductive layer 30 is
provided. Also as shown in FIG. 19, the sense micro-wires 54 are
printed or transferred on the dielectric layer 40; no separate
sense layer 50 is formed, although the protective overcoat layer 70
(not shown) can be provided and can serve as the sense layer 50, if
desired.
[0101] In all these various embodiments, the various layers can
alternatively be pre-made and laminated together. Optically clear
adhesives can be used as can conductive adhesives, if desired, for
example to electrically connect the unpatterned conductive layer 30
to the drive micro-wires 24. In such an embodiment, the conductive
adhesive is considered to be part of the unpatterned conductive
layer 30.
[0102] In an embodiment of the present invention, the electrical
resistance of the unpatterned conductive layer 30 is greater than
the resistance of each of the drive electrodes 22. The resistance
of the unpatterned conductive layer 30 was measured as the sheet
resistance of the unpatterned conductive layer 30 independently of
the drive micro-wires 24. The resistance of the drive electrodes 22
is the resistance measured along the length of the drive electrode
22.
[0103] 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 drive electrodes 22 are driven
and on the drive current and voltage characteristics and on the
conductivity of the drive electrodes 22.
[0104] In another embodiment, the resistance of the unpatterned
conductive layer 30 between any two drive 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 two drive electrodes
22. For example, as illustrated in FIG. 28, the unpatterned
conductive layer 30 is in electrical contact with the drive
electrodes 22. The drive electrodes 22 are made up of drive
micro-wires 24. The sense electrodes 52, made up of sense
micro-wires 54, are separated from the drive electrodes 22 by the
dielectric layer 40 (FIG. 27, not shown in the plan view of FIG.
28). The drive electrodes 22 are arranged in an array and separated
by a gap 60. The sense electrodes 52 are arranged in an array
orthogonal to the array of drive electrodes 22. Thus, in this
example, the resistance of the unpatterned conductive layer 30
between drive electrodes 22 separated by the gap 60 is at least ten
times greater than the resistance of any of the drive electrodes
22. The conductive material in the unpatterned conductive layer 30
can extend over the substrate 10 beyond the area 31 but outside the
area 31 the conductive material can be, but is not necessarily,
patterned.
[0105] In various embodiments of the present invention, the
resistance of the unpatterned conductive layer 30 can be adjusted
to compensate for any unwanted conductivity between adjacent drive
electrodes 22. Although the dummy micro-wires 90 extend along
equi-potential lines or the dummy micro-dots have a limited extent
and an aspect ratio of approximately one, the dummy micro-wires 90
and dummy micro-dots 92 do have a physical width and therefore they
do have some conductivity. If the dummy micro-wires 90 and dummy
micro-dots 92 are made with common materials and in a common step
with the driver micro-wires 24, the physical width of the dummy
micro-wires 90 and dummy micro-dots 92 will slightly decrease the
resistance between adjacent driver electrodes 22. This slight
decrease can be compensated by a corresponding slight reduction in
the conductivity of the unpatterned conductive layer 30, for
example by changing the material composition of the unpatterned
conductive layer 30 or by reducing the thickness of the unpatterned
conductive layer 30.
[0106] In a further embodiment of the present invention, a driver,
for example an integrated circuit, for driving the drive electrodes
22 provides voltage and current to the drive electrodes 22 in a
desired drive waveform having a period and frequency. The frequency
of the drive waveform limits the rate at which the capacitance
between the drive and sense electrodes 22, 52 can be measured.
Because the unpatterned conductive layer 30 is electrically
connected to the drive electrode 22 and has a limited conductivity,
the rate at which the drive electrode 22 and the unpatterned
conductive layer 30 can be charged is likewise limited. A
micro-wire electrode, such as the drive electrode 22, has gaps 26
between the micro-wires in the micro-wire electrode that, according
to the present invention, are bridged 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 drive micro-wires 24
in the drive electrode 22, the rate at which the drive 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 drive electrode 22 and the center of
the open area in response to a voltage change as provided by the
drive waveform. Therefore, according to the further embodiment of
the present invention, the sheet resistance of the unpatterned
conductive layer 30, including the dummy micro-wires 90 or dummy
micro-dots 92, is sufficiently low that the time constant for
charging the center of the open area between drive micro-wires 24
in the drive electrode 22 is less than the period of a drive
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.
[0107] In operation, a touch-screen controller (for example
touch-screen controller 140 of FIG. 27) energizes one of the drive
electrodes 22 and senses one of the sense electrode 52 to detect
the capacitance, charge, or current or changes in capacitance,
charge, or current of the area overlapped by the one drive
electrode 22 and one sense electrode 52. Since the unpatterned
conductive layer 30 electrically connects the drive electrodes 22,
some current leaks from the driven drive electrode 22 to other
drive electrodes 22. However, because the resistance of the
unpatterned conductive layer 30 is high relative to the resistance
of the drive 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 sense
electrode 52, especially if the electromagnetic interference
originates from a side of the unpatterned conductive layer 30
opposite the sense electrodes 52. Furthermore, the unpatterned
conductive layer 30 assists in extending the electrical field
produced by driving the drive micro-wires 24 in the one drive
electrode 22 into the spaces between the drive micro-wires 24,
thereby providing a more uniform field between the drive electrode
22 and the sense 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 drive
micro-wires 24 of the drive electrodes 22 and the sense micro-wires
54 of the sense electrodes 52.
[0108] In comparison to other prior-art solutions using a separate
ground plane beneath drive 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. Moreover, the use of dummy
micro-wires 90 or dummy micro-dots 92 provides optical uniformity
over the touch-screen area 31.
[0109] If prior-art dummy micro-wires 152, for example those
illustrated in FIG. 33 having a typical arrangement corresponding
to the arrangement of the electrode micro-wires 150, are used in
combination with the unpatterned conductive layer 30 of the present
invention, the unpatterned conductive layer 30 and the prior-art
dummy micro-wires 152 will electrically short the separate drive
electrodes 22 together so that they cannot function. Furthermore,
the pitch of the electrode micro-wires 24 anticipated in practical
applications is so large that electromagnetic interference can
readily pass through the electrode micro-wires 24 or prior-art
dummy micro-wires 152 in the absence of the unpatterned conductive
layer 30. Hence, prior-art dummy micro-wire arrangements cannot be
used with the unpatterned conductive layer 30 of the present
invention without destroying the functionality of the unpatterned
conductive layer 30 and the electrodes 22.
[0110] Referring again to FIG. 6, a method of the present invention
includes providing a plurality of patterned drive electrodes 22,
for example on the substrate 10, each drive electrode 22 including
a plurality of patterned conductive electrically connected
micro-wires 24 and any dummy micro-wires 90 or dummy micro-dots 92
at the same time in simultaneous steps 500 and 505. The unpatterned
conductive layer 30 is located in electrical contact with the drive
electrodes 22 in step 510. The dielectric layer 40 is located
adjacent to the unpatterned conductive layer 30 in step 515. A
plurality of patterned sense electrodes 52, each sense electrode 52
including a plurality of patterned conductive electrically
connected micro-wires 54 is located over the dielectric layer 40 so
that the dielectric layer 40 is located between the drive
electrodes 22 and the sense electrodes 52 in step 520.
[0111] A variety of techniques are usable to construct a touch
screen device of the present invention. In various embodiments, the
patterned drive electrodes 22 are formed in a layer, such as drive
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 drive
electrodes 22 or drive layer 20. 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 sense electrodes 52
are formed in a layer, such as sense 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.
[0112] In an embodiment, unpatterned conductive layer 30 or
dielectric layer 40 is deposited by sputtering or deposition and
patterned outside the touch-sensitive area 31 either with masks or
by photolithographic processes. In an embodiment, conductive
material is only deposited in the touch-sensitive area 31.
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 31. 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 31 is accomplished, for
example, by masking the deposition, using patterned deposition
inhibitors, or by photolithographic processes.
[0113] Alternatively or in addition, referring to FIG. 29, the
substrate 10 is provided in step 200, together with imprinting
stamps in step 205. The drive layer 20 is provided on the substrate
10, for example by coating in step 210. The patterned drive
electrodes 22 are formed by imprinting the drive layer 20 with an
imprinting stamp to form micro-channels in step 215, curing the
drive layer 20 to form drive micro-channels in step 220 that are
filled with conductive ink in step 230. The conductive ink is cured
in step 235 to form drive micro-wires 24, dummy micro-wires 90, or
dummy micro-dots 92. The unpatterned conductive layer 30 is coated
over the drive micro-wires 24, dummy micro-wires 90, or dummy
micro-dots 92 in step 300 and the dielectric layer 40 is coated
over the unpatterned conductive layer 30 in step 305. The
unpatterned conductive layer 30 is provided on the drive layer 20,
for example by coating in step 300. The dielectric layer 40 is
coated over the unpatterned conductive layer 30 in step 305 and the
sense layer 50 in step 310. Alternatively, the separate dielectric
layer 40 is not coated and the sensor layer 50 also serves as the
dielectric layer (as shown for example in FIG. 1A). The patterned
sense electrodes 52 are formed by imprinting the sense layer 50
with an imprinting stamp to form micro-channels in step 315, the
sense layer 50 is cured to form sense micro-channels in step 320,
and the sense micro-channels are filled with conductive ink in step
330. The conductive ink is cured in step 335 to form sense
micro-wires 54. The protective overcoat layer 70 is optionally
coated in step 400.
[0114] In other embodiments, imprinting methods are used to imprint
drive micro-channels in the dielectric layer 40 (as shown in FIG.
21) or in the unpatterned conductive layer 30 (as shown in FIG.
18). Similarly, in other embodiments imprinting methods are used to
imprint sense micro-channels in the dielectric layer 40 (as shown
in FIG. 20). Likewise, the order of construction of the drive layer
20 and the sense layer 50 can be reversed.
[0115] 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. For example, in
FIGS. 16 and 18, drive micro-wires are printed or transferred onto
the unpatterned conductive layer 30. Referring to FIG. 17, drive
micro-wires 24, dummy micro-wires 90, or dummy micro-dots 92 are
printed on or transferred to the substrate 10 and then coated with
unpatterned conductive layer 30. Likewise, as shown in FIG. 23, the
sense electrodes 52 are printed on or transferred to the dielectric
layer 40 and then coated with the sense layer 50.
[0116] 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.
[0117] In yet another embodiment, layer structures are laminated to
another layer. Referring to FIG. 15, for example, the drive layer
20 is made as a separate construction (for example as a layer of
PET) including drive micro-wires 24, dummy micro-wires 90, or dummy
micro-dots 92 and then laminated with an adhesive to substrate 10.
Sense 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.
[0118] In various embodiments, the unpatterned conductive layer 30
is laminated, coated, or deposited on the drive 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 drive
electrodes 22 or sense electrodes 52.
[0119] 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, sputter or coating through a mask or blanket coated and
patterned using known photo-lithographic methods. Such known
photo-lithographic technology can include a photo-sensitive
material that is optically patterned through a mask to cure the
photo-sensitive material and removal of uncured material.
[0120] 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).
[0121] 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.
[0122] 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.
[0123] 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, can be
transparent, and can have opposing substantially parallel and
extensive surfaces. 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.
[0124] In various embodiments 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.
[0125] Electrically conductive micro-wires and methods of the
present invention are useful for making electrical conductors and
busses for transparent micro-wire electrodes, dummy micro-wires 90,
or dummy micro-dots 92 and electrical conductors in general, for
example as used in electrical busses. A variety of micro-wire
patterns are used and the present invention is not limited to any
one pattern. Micro-wires 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.
[0126] 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.
[0127] 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. 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.
[0128] 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.
[0129] 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.
[0130] 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.
[0131] Curable inks provided in a liquid form are deposited or
located in drive or sense micro-channels and cured, for example by
heating or exposure to radiation such as infra-red light, visible
light, or ultra-violet radiation. The curable ink hardens to form
the cured ink that makes up drive or sense micro-wires 24, 54,
dummy micro-wires 90, or dummy micro-dots 92. For example, a
curable conductive ink with conductive nano-particles are located
within drive or sense micro-channels and cured by heating or
sintering to agglomerate or weld the nano-particles together,
thereby forming an electrically conductive drive or sense
micro-wire 24, 54. Materials, tools, and methods are known for
coating liquid curable inks to form micro-wires.
[0132] 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.
[0133] 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.
[0134] 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.
[0135] 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.
[0136] 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
[0137] Referring to FIG. 30, sense electrodes 52 including sense
micro-wires 54 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 consisting of connected open
right-angle-diamond electrodes, 1600 .mu.m on diagonal. The
periodic width of the sense electrodes 52 was 6.42 mm separated by
400 micron breaks in the sense micro-wires 54 at intersections
between sense electrodes 52. The sense electrodes 52 were
terminated with conductive rectangular pads to enable simple
resistance measurements end-to-end. The pads at one end of the
sense electrodes 52 also had conductive buss lines leading to
additional pads at the edge of the support (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. Sense electrode 52 resistance was
measured to be on the order of 450.OMEGA. from end-to-end and
essentially infinite between nearest neighbor electrodes.
[0138] Drive electrodes 22 were prepared as were the sense
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 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. Drive 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 drive resistance in this
inventive example was 356 to 1.
[0139] A functional touch-screen was fabricated from the prepared
sense and drive electrodes 52, 22 by first, laminating a cover
sheet of 4 mil PET (protective overcoat layer 70) on the exposed
side of the sense electrodes 52 on dielectric layer 40 using
optically clear adhesive (first optically clear adhesive layer 80),
OCA (Adhesives Research, ARClear 8154 Optically Clear Unsupported
Transfer Adhesive) to form a coversheet of the touch-screen
example. Sense electrodes 52 were oriented 90 degrees with respect
to drive electrodes 22 and offset such that the intersections of
the diamonds were directly above the center of the diamonds of the
drive 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 as a second
optically clear adhesive layer 82. The dielectric thus includes
both the OCA (second optically clear adhesive layer 82) and the 4
mil PET dielectric layer 40.
Comparative Example
[0140] 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
[0141] The measurement apparatus consisted of 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 consisted of a compliant, conductor loaded polymer foam
mounted on the end of a conductive rod. All but one drive electrode
22 were held at ground while a voltage waveform consisting of a
controlled burst of sine waves (either 100 kHz or 1 MHz) was
applied to one of the drive electrodes 22. All of the sense
electrodes 52 were held at ground and one was connected to a charge
sensitive pre-amplifier (operational amplifier with capacitor
feedback) which held the sense 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.
[0142] 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-sense
controller resulting in improved system efficiency.
[0143] 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 sense and drive 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.
p
Touch-Sensitivity=-(C.sub.touch-C.sub.no.sub.--.sub.touch)/C.sub.no.su-
b.--.sub.touch
[0144] 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 sense and drive electrodes in
each example.
[0145] To test the shielding properties, connections to the sense
and drive electrodes 52, 22 were exchanged thus reversing the roles
of the drive and sense 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 drive 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 shorting between drive 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.
[0146] The optical uniformity of the dummy micro-wires 90 and dummy
micro-dots 92 located between electrodes 20 were tested using image
patterns displayed on a high-resolution monitor at standard viewing
distances. Dummy micro-wires 90 arranged in lines along different
equi-potential lines and dummy micro-wires 90 arranged in dashed
lines along different equi-potential lines were both tested with
electrode micro-wires arranged as shown in the drive layer 20 of
FIG. 1A. When the length and number of dummy micro-wires 90 were
chosen to match the electrode micro-wires 22, no visible difference
in optical uniformity between the drive electrode 22 and the gap 26
was observed. Dummy micro-dots 92 were also tested. The dummy
micro-dots were arranged in lines, in a regular two-dimensional
array (e.g. as in FIG. 10), and in a random arrangement. In every
case, no visible difference in optical uniformity between the drive
electrode 22 and the gap 26 was observed.
[0147] 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.
[0148] In addition to the inventive and comparative examples
described, a touch-screen structure 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 drive micro-wires 24 was formed using
atomic-layer deposition methods.
[0149] 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.
[0150] 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
[0151] B cross section line C cross section line 5 micro-wire
multi-electrode structure 10 substrate 11 touch surface 20 drive
layer/electrode layer 22 drive electrode/electrode 23 edge
electrode 24 drive micro-wire/micro-wire 26, 26A, 26B drive gap/gap
30 unpatterned conductive layer 31 area/touch-sensitive area 33
area edge 40 dielectric layer 50 sense layer 52 sense electrode 54
sense micro-wire 57 sense gap 60 gap 70 protective overcoat layer
80 first optically clear adhesive layer 92 second optically clear
adhesive layer 90, 90A, 90B equi-potential dummy micro-wires 92,
92A, 92B dummy micro-dots 94 additional dummy micro-wires 95
additional dummy micro-dots 96 edge dummy micro-wires 98 edge dummy
micro-dots 100 display and touch-screen apparatus 110 display Parts
List cont'd 120 touch screen 122 first transparent substrate 124
dielectric layer 126 second transparent substrate 128 touch pad
area 130 first transparent electrode 132 second transparent
electrode 134 wires 136 electrical buss connections 140
touch-screen controller 142 display controller 150 micro-wire 152
dummy micro-wire 156 micro-pattern 200 provide substrate step 205
provide stamps step 210 provide drive layer step 215 imprint drive
micro-channels step 220 cure drive micro-channels step 230 provide
conductive ink in drive micro-channels step 235 cure conductive ink
in drive micro-channels step 300 coat conductive layer step 305
coat dielectric layer step 310 provide sense layer step 315 imprint
sense micro-channels step 320 cure sense micro-channels step 330
provide conductive ink in sense micro-channels step 335 cure
conductive ink in sense micro-channels step 400 optional coat
overcoat step Parts List cont'd 500 provide drive micro-wire
electrode step 505 provide dummy micro-wire step 510 locate
unpatterned conductive layer step 515 locate dielectric layer step
520 provide sense micro-wire electrode step
* * * * *