U.S. patent application number 11/818335 was filed with the patent office on 2008-07-10 for touch screen stack-up processing.
This patent application is currently assigned to Apple Inc.. Invention is credited to Mark Arthur Hamblin, Steve Porter Hotelling, Brian Richards Land.
Application Number | 20080165139 11/818335 |
Document ID | / |
Family ID | 39593851 |
Filed Date | 2008-07-10 |
United States Patent
Application |
20080165139 |
Kind Code |
A1 |
Hotelling; Steve Porter ; et
al. |
July 10, 2008 |
Touch screen stack-up processing
Abstract
A multi-touch sensor panel is disclosed that can be produced by
forming a plurality of first traces of substantially transparent
conductive material on a first substrate, forming a plurality of
second traces of the substantially transparent material, and
creating a fluid-tight gap between the plurality of first traces
and the plurality of second traces. The fluid-tight gap can then be
filled with a fluid having substantially no bubbles and an optical
index similar to the optical index of the first and second traces
to make the gap and the first and second traces substantially
transparent. The second and first traces can be oriented to cross
over each other at crossover locations separated by the fluid, the
crossover locations forming mutual capacitance sensors for
detecting touches.
Inventors: |
Hotelling; Steve Porter;
(San Jose, CA) ; Land; Brian Richards; (Redwood
City, CA) ; Hamblin; Mark Arthur; (San Francisco,
CA) |
Correspondence
Address: |
APPLE C/O MORRISON AND FOERSTER ,LLP;LOS ANGELES
555 WEST FIFTH STREET SUITE 3500
LOS ANGELES
CA
90013-1024
US
|
Assignee: |
Apple Inc.
Cupertino
CA
|
Family ID: |
39593851 |
Appl. No.: |
11/818335 |
Filed: |
June 13, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60878797 |
Jan 5, 2007 |
|
|
|
Current U.S.
Class: |
345/173 ; 369/1;
455/422.1 |
Current CPC
Class: |
G06F 2203/04104
20130101; G09G 3/36 20130101; G06F 2203/04105 20130101; G06F
3/04164 20190501; G06F 3/0412 20130101; G06F 3/0445 20190501; G06F
2203/04111 20130101; G06F 3/041 20130101; G06F 2203/04101 20130101;
G06F 3/045 20130101; G06F 3/0446 20190501; G06F 3/0447
20190501 |
Class at
Publication: |
345/173 ; 369/1;
455/422.1 |
International
Class: |
G06F 3/041 20060101
G06F003/041 |
Claims
1. A method for forming a multi-touch sensor panel, comprising:
forming a plurality of first traces of substantially transparent
conductive material on a first substrate; forming a plurality of
second traces of the substantially transparent material; creating a
fluid-tight gap between the plurality of first traces and the
plurality of second traces; filling the fluid-tight gap with a
fluid having substantially no bubbles and an optical index similar
to the optical index of the first and second traces to make the gap
and the first and second traces substantially transparent; and
orienting the second and first traces to cross over each other at
crossover locations separated by the fluid, the crossover locations
forming mutual capacitance sensors for detecting touches.
2. The method of claim 1, wherein the first substrate is a cover
glass having a first side capable of being touched, and a second
side opposite the first side on which the plurality of first traces
are formed.
3. The method of claim 2, further comprising forming the plurality
of second traces on a second substrate.
4. The method of claim 1, further comprising creating the
fluid-tight gap by forming compressible spacers between the first
and second traces, the compressible spacers capable of being
compressed during a touch and changing a mutual capacitance of the
mutual capacitance sensors.
5. The method of claim 1, further comprising coupling a chip on
glass to the first substrate, the chip on glass including sensor
panel circuitry.
6. A method for forming a multi-touch sensor panel, comprising:
forming a plurality of first traces and a plurality of second
traces of substantially transparent conductive material; orienting
the plurality of second and first traces to cross over each other
at crossover locations, the crossover locations forming mutual
capacitance sensors for detecting touches; separating the second
and first traces by a fluid having substantially no bubbles and an
optical index similar to the optical index of the first and second
traces to make the first and second traces substantially
transparent.
7. The method of claim 6, further comprising forming the plurality
of first traces on a second side of a first substrate having a
first side capable of being touched, the second side opposite the
first side.
8. The method of claim 7, further comprising forming the plurality
of second traces on a second substrate.
9. The method of claim 6, further comprising separating the second
and first traces using compressible spacers, the compressible
spacers capable of being compressed during a touch and changing a
mutual capacitance of the mutual capacitance sensors.
10. The method of claim 7, further comprising coupling a chip on
glass to the first substrate, the chip on glass including sensor
panel circuitry.
11. A multi-touch sensor panel, comprising: a first substrate
having a plurality of first traces of substantially transparent
conductive material formed thereon; a plurality of second traces of
the substantially transparent material; a fluid-tight gap formed
between the plurality of first and second traces; and a fluid
having substantially no bubbles and an optical index similar to the
optical index of the plurality of first and second traces held
within the fluid-tight gap, the fluid for making the gap and the
plurality of first and second traces substantially transparent;
wherein the plurality of first and second traces are oriented to
cross over each other at crossover locations separated by the
fluid, the crossover locations forming mutual capacitance sensors
for detecting touches.
12. The multi-touch sensor panel of claim 11, wherein the first
substrate is a cover glass having a first side capable of being
touched, and a second side opposite the first side on which the
plurality of first traces are formed.
13. The multi-touch sensor panel of claim 12, further comprising a
second substrate having the plurality of second traces formed
thereon.
14. The multi-touch sensor panel of claim 11, further comprising
compressible spacers coupled between the plurality of first and
second traces, the compressible spacers capable of being compressed
during a touch and changing a mutual capacitance of the mutual
capacitance sensors.
15. The multi-touch sensor panel of claim 11, further comprising a
chip on glass coupled to the first substrate, the chip on glass
including sensor panel circuitry.
16. The multi-touch sensor panel of claim 11, further comprising a
liquid crystal display (LCD) module coupled to the multi-touch
sensor panel.
17. The multi-touch sensor panel of claim 16, the multi-touch
sensor panel incorporated into a computing system.
18. The multi-touch sensor panel of claim 17, the computing system
incorporated into a mobile telephone.
19. The multi-touch sensor panel of claim 17, the computing system
incorporated into a digital audio player.
20. A mobile telephone including a multi-touch sensor panel, the
multi-touch sensor panel comprising: a first substrate having a
plurality of first traces of substantially transparent conductive
material formed thereon; a plurality of second traces of the
substantially transparent material; a fluid-tight gap formed
between the plurality of first and second traces; and a fluid
having substantially no bubbles and an optical index similar to the
optical index of the plurality of first and second traces held
within the fluid-tight gap, the fluid for making the gap and the
plurality of first and second traces substantially transparent;
wherein the plurality of first and second traces are oriented to
cross over each other at crossover locations separated by the
fluid, the crossover locations forming mutual capacitance sensors
for detecting touches.
21. A digital audio player including a multi-touch sensor panel,
the multi-touch sensor panel comprising: a first substrate having a
plurality of first traces of substantially transparent conductive
material formed thereon; a plurality of second traces of the
substantially transparent material; a fluid-tight gap formed
between the plurality of first and second traces; and a fluid
having substantially no bubbles and an optical index similar to the
optical index of the plurality of first and second traces held
within the fluid-tight gap, the fluid for making the gap and the
plurality of first and second traces substantially transparent;
wherein the plurality of first and second traces are oriented to
cross over each other at crossover locations separated by the
fluid, the crossover locations forming mutual capacitance sensors
for detecting touches.
22. A multi-touch sensor panel, comprising: a plurality of first
traces and a plurality of second traces of substantially
transparent conductive material, the plurality of second and first
traces oriented to cross over each other at crossover locations,
the crossover locations forming mutual capacitance sensors for
detecting touches; and a fluid separating the second and first
traces, the fluid having substantially no bubbles and an optical
index similar to the optical index of the first and second traces
to make the first and second traces substantially transparent.
23. The multi-touch sensor panel of claim 22, further comprising a
first substrate upon which the plurality of first traces are
formed, the first substrate being a cover glass having a first side
capable of being touched, and a second side opposite the first side
upon which the plurality of first traces are formed.
24. The multi-touch sensor panel of claim 23, further comprising a
second substrate having the plurality of second traces formed
thereon.
25. The multi-touch sensor panel of claim 22, further comprising
compressible spacers coupled between the plurality of first and
second traces, the compressible spacers capable of being compressed
during a touch and changing a mutual capacitance of the mutual
capacitance sensors.
26. The multi-touch sensor panel of claim 22, further comprising a
chip on glass coupled to the plurality of first traces, the chip on
glass including sensor panel circuitry.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present invention claims the benefit under 35 USC 119(e)
of U.S. provisional patent application Ser. No. 60/878,797 filed
Jan. 5, 2007, the contents of which are incorporated by reference
herein.
FIELD OF THE INVENTION
[0002] This relates to touch screens, and more particularly, to
methods and processes for forming the stack-up of materials
comprising the touch screens.
BACKGROUND OF THE INVENTION
[0003] Many types of input devices are presently available for
performing operations in a computing system, such as buttons or
keys, mice, trackballs, touch panels, joysticks, touch screens and
the like. Touch screens, in particular, are becoming increasingly
popular because of their ease and versatility of operation as well
as their declining price. Touch screens can include a touch panel,
which can be a clear panel with a touch-sensitive surface. The
touch panel can be positioned in front of a display screen so that
the touch-sensitive surface can cover the viewable area of the
display screen. Touch screens can allow a user to make selections
and move a cursor by simply touching the display screen via a
finger or stylus. In general, the touch screen can recognize the
touch and position of the touch on the display screen, and the
computing system can interpret the touch and thereafter perform an
action based on the touch event.
[0004] Touch panels can include an array of touch sensors capable
of detecting touch events (the touching of fingers or other objects
upon a touch-sensitive surface). Future panels may be able to
detect multiple touches (the touching of fingers or other objects
upon a touch-sensitive surface at distinct locations at about the
same time) and near touches (fingers or other objects within the
near-field detection capabilities of their touch sensors), and
identify and track their locations. Examples of multi-touch panels
are described in Applicants co-pending U.S. application Ser. No.
10/842,862 entitled "Multipoint Touchscreen," filed on May 6, 2004
and published as U.S. Published Application No. 2006/0097991 on May
11, 2006, the contents of which are incorporated by reference
herein.
[0005] Various materials, adhesives, and processing steps are
required to make a touch screen stackup that is functional,
cost-effective, and space-efficient.
SUMMARY OF THE INVENTION
[0006] A multi-touch sensor panel can be produced by first forming
a plurality of first traces of substantially transparent conductive
material on a first substrate, forming a plurality of second traces
of the substantially transparent material, and creating a
fluid-tight gap between the plurality of first traces and the
plurality of second traces. The fluid-tight gap can then be filled
with a fluid having substantially no bubbles and an optical index
similar to the optical index of the first and second traces to make
the gap and the first and second traces substantially transparent.
The second and first traces can be oriented to cross over each
other at crossover locations separated by the fluid, the crossover
locations forming mutual capacitance sensors for detecting
touches.
[0007] In particular, a touch screen can be formed by first forming
column traces on the back of a cover glass, forming row traces on
the top of a substrate, and laminating the cover glass and
substrate together with spacers in between, forming a fluid-tight
gap. The fluid-tight gap can be filled with fluid having optical
properties similar to the row and column traces. Integrated
circuits (ICs) and flexible printed circuits (FPCs) can be bonded
to the cover glass and encapsulated. The cover glass and substrate
can further be bonded to an LCD module. Alternatively, both the
column and row traces can be formed on the back side of the cover
glass, separated by an insulator with dielectric properties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIGS. 1a through 1n illustrate an exemplary first
touchscreen that can be formed by combining an exemplary first
upper layer subassembly, an exemplary first lower layer
subassembly, and an exemplary LCD module according to one
embodiment of this invention.
[0009] FIGS. 2a through 2c illustrate an exemplary second
touchscreen that can be formed by combining the exemplary first
upper layer subassembly, an exemplary second lower layer
subassembly, and the exemplary LCD module according to one
embodiment of this invention.
[0010] FIGS. 3a through 3e illustrate an exemplary third
touchscreen that can be formed by combining the exemplary first
upper layer subassembly, an exemplary third lower layer
subassembly, and the exemplary LCD module according to one
embodiment of this invention.
[0011] FIGS. 4a through 4j illustrate an exemplary fourth
touchscreen that can be formed by an exemplary second upper layer
subassembly and the exemplary LCD module according to one
embodiment of this invention.
[0012] FIGS. 5a through 5d illustrate an exemplary fifth
touchscreen that can be formed by an exemplary third upper layer
subassembly and the exemplary LCD module according to one
embodiment of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] In the following description of preferred embodiments,
reference is made to the accompanying drawings which form a part
hereof, and in which it is shown by way of illustration specific
embodiments in which the invention may be practiced. It is to be
understood that other embodiments may be utilized and structural
changes may be made without departing from the scope of the
preferred embodiments of the present invention.
[0014] It should be understood that in all of the figures and
descriptions that follow, the listed materials, properties and
dimensions (listed in units of millimeters unless otherwise noted)
are merely exemplary in nature and are not intended to limit the
scope of the invention.
[0015] FIGS. 1a through 1n illustrate an exemplary first
touchscreen that can be formed by combining an exemplary first
upper layer subassembly, an exemplary first lower layer
subassembly, and an exemplary LCD module according to one
embodiment of this invention. The exemplary first touchscreen of
FIGS. 1a-1n can also include force-sensitive touch screens.
[0016] FIGS. 1a through 1c illustrate an exemplary first upper
layer subassembly for a touch sensor panel according to embodiments
of the invention. FIG. 1a shows top glass or motherglass substrate
100, which can be a large sheet (e.g. 2.times.3 feet) from which a
number of individual substrates can be generated. A chemical
strengthening step can be performed on the top glass, which can
involve applying a nitric acid bath at high heat to glass 100,
resulting in compressive forces or stresses in the surface layer of
the glass and tensile stresses in the interior core of the glass
that can make the surface of the glass less likely to crack apart.
Anti-glare coating 102 can then be deposited on glass 100.
Anti-glare coating 102 can be particle-embedded silicon dioxide.
Alternatively, anti-reflective (AR) coating, or a plain glass
surface with no coating, can be used. Black mask 104 can be applied
to border regions of glass 100. Black mask 104 can be applied using
printing techniques, roller coating, or sputtering followed by
etching of unwanted areas. Alternatively the black mask can be
applied using spin coating or extrusion coating of photo-imagable
black polymer, and selectively removed with photolithography
(similar to the process to create black mask for LCD color
filters). Note that FIG. 1a shows that black mask 104 has been
applied in a border region, but has been stripped away in a clear
center region. Next, clear overcoat 106 can be applied over black
mask 104 and glass 100. Substantially clear overcoat 106 can be a
clear polymer that can be curable with ultraviolet (UV) light.
Substantially clear overcoat 106 can smooth over the step between
the black mask and non-black mask areas, and can form a
substantially planar surface for subsequent Indium Tin Oxide (ITO)
sputtering and metal patterning. ITO 108 of 10 to 200 ohms per
square (max) and an optical index of n=1.8 can then be sputtered
over overcoat 106, although thicker layers of ITO can reduce this
resistance and thinner layers can increase this resistance. The
center region can be masked to protect the transparent center
region from subsequent metal sputtering by photo-imaging or
printing photoresist 110 with an overlap of about 100 microns.+-.50
microns with respect to black mask 104 using silkscreen techniques.
Metal 112 having a resistivity of 0.2 ohms per square can then be
sputtered over ITO 108 and photoresist 110. Metal 112 can be a
stack-up of different metals, such as aluminum (for high
connectivity) and molybdenum (to prevent corrosion), copper, or a
silver alloy.
[0017] FIG. 1b shows the step of removing photoresist 110 by
peeling the photoresist off or submersing it into an acid that
attacks the photoresist but not the metal. For each part, this step
can form a metal ring around the transparent region of the touch
screen.
[0018] FIG. 1c shows the patterning of metal 112 using
photolithography that can form metal traces having 10 micron
(minimum) widths and spaces along the borders of the touch screen,
and then further patterning ITO 108 using photolithography to form
row or column traces having 10 to 30 micron (minimum) widths and
spaces. Border insulator 114 of 5 to 10 micron thickness can then
be printed over ITO 108 to create a fluid-tight ring around each
touch screen.
[0019] FIG. 1d illustrates an exemplary first lower layer
subassembly according to embodiments of the invention. FIG. 1d
shows bottom glass or motherglass substrate 116, which can be a
large sheet (e.g. 2.times.3 feet), and from which a number of
individual substrates can be generated. Substantially clear
overcoat 118 of silicon dioxide or polymer can then be applied over
bottom glass 116 to prepare the surface for ITO. This overcoat can
be optional. ITO 120 having a resistivity of 10 to 200 ohms per
square and an optical index of 1.8 can then be sputtered over clear
overcoat 118. ITO 120 can then be patterned using photolithography.
Spacers 122 of clear silicon ink having an optical index of 1.8, or
an optical index substantially similar to the fluid that will be
used, which provide a spacing between the top and bottom glass, can
then be printed over ITO 120 and clear overcoat 118 and can be
cured using ultraviolet (UV) light. In border areas (the left two
spacers in FIG. 1d), the border spacers can be a solid pattern
12.+-.2 microns in height, except for where via openings exist. In
other areas, the spacers can be dots of 50.+-.10 micron diameter
12.+-.2 microns in height. If the touch screen is to include force
sensing, spacers 122 can be made of a soft, elastic material such
as clear, UV-cured silicon ink that has can have an optical index
that matches that of ITO to minimize pattern visibility. If the
touch screen does not include force sensing, the spacer dots can be
made of a harder, inelastic material. Assembly adhesive 124 such as
clear silicon ink having an optical index of 1.8 can then be
printed onto spacer 122 using the same pattern as the spacers. Note
that adhesive 124 is not immediately UV-cured so it can act as an
adhesive. Conductive vias 126 having a diameter of 500 microns can
then be deposited between the border spacers using a silk-screening
process or a robot needle dispenser. Vias 126 can be made of
conductive epoxy or ink and can provide electrical connections
between the top and bottom glass. Vias 126 can allow the
consolidation of all connections onto a single layer.
[0020] FIG. 1e shows the previously described first upper layer
subassembly and the first lower layer subassembly bonded together
with assembly adhesive 124 to form a first touch sensor panel
assembly, with UV light 126 applied through the bottom glass to
cure the assembly adhesive. A fluid-tight gap 199 is can be formed
between the first upper layer subassembly and the first lower layer
subassembly.
[0021] FIG. 1f shows the step of scribing, where laser or wheel 128
can be used to introduce stresses into the glass so that the
motherglass can be broken into individual parts.
[0022] FIG. 1g shows the step of breaking away unwanted parts of
the assembly at the scribe lines created by the stresses. The view
shown is along the short edge of the exemplary first upper layer
subassembly, as shown in the thumbnail. Note that the scribe lines
are offset, so that when the unwanted parts are broken away, ledge
101 can be used for flex circuit connections.
[0023] FIG. 1h shows fluid-tight gaps 199 between the first upper
and lower layer subassemblies that can be filled with clear optical
fluid 130 having an optical index that can be similar to that of
the ITO 120 and spacers 122 to make the ITO patterns and spacers
substantially transparent. If force-sensing is not required, fluid
130 could instead be a liquid glue that can be curable with UV
light to make a solid stackup. Fluid 130 can have dielectric
properties which enable the row and column traces that can be
formed in ITO layers 120 and 108 to experience a mutual capacitance
between them at crossover points and act as touch sensors. If
force-sensing is employed, the change in the distance between ITO
layers 120 and 108 during a touch can change the mutual capacitance
experienced by each of the touch sensors, effectively representing
a measure of force. IC 132, which can have a height of 0.35 and a
width of 1.5, can then be bonded to metal traces 112 on the top
glass using anisotropic conductive film (ACF) 134. Flexible printed
circuit (FPC) 136 (e.g. a 2-layer FPC) can also be bonded to metal
traces 112 on the top glass using ACF 138.
[0024] Because the use of PSA to fully laminate the exemplary first
upper and lower layer subassemblies together can cause bubbles to
form in the PSA, thereby reducing the clarity of the touch sensor
panel, in embodiments of the invention fluid 130 can be used in
some areas instead of full lamination for the purpose of providing
optical index matching with few or no bubbles.
[0025] FIG. 1i shows FPC 136 that can be folded away from the edge
of top glass 100, and a temporary mold, which is indicated by
reference numbers 140 and 141 in FIG. 1i, can be positioned to
enable encapsulent 142 to be poured and retained by the mold (note
that FIG. 1i is oriented up-side down relative to the time at which
the encapsulent is poured). Encapsulation can provide a physically
robust touch screen and locks FPC 136 and IC 132 into place.
[0026] FIG. 1j shows the step of removing temporary molds 140 and
141 after encapsulent 142 has cured, exposing support ledge 144
which can be 0.8 wide and useful for mounting the touch screen into
a bezel of a product.
[0027] FIG. 1k shows the step of final outline cutting using laser
or wheel 146 to create the final perimeter.
[0028] FIG. 1l shows the step of edge finishing at edge 197, where
grinding and polishing can be used to create radii at the four
corners for strength and safety.
[0029] FIG. 1m shows the first touch sensor panel assembly that can
be bonded or laminated to LCD module 119 using optically
substantially clear adhesive 148 to form the exemplary first
touchscreen, where the LCD module can include LCD polarizer 121,
LCD top glass, liquid crystal, and LCD bottom glass. LCD frame 150
can mount to ledge 144.
[0030] FIG. 1n shows a side detail of the exemplary first
touchscreen, which can include metal traces 112 in the border
areas. The view shown has now changed to along the long edge of the
exemplary first touchscreen, as shown in the thumbnail.
[0031] FIGS. 2a through 2c illustrate an exemplary second
touchscreen that can be formed by combining the exemplary first
upper layer subassembly, an exemplary second lower layer
subassembly, and the exemplary LCD module according to one
embodiment of this invention. The exemplary second touchscreen of
FIGS. 2a through 2c can also include force-sensitive touch
screens.
[0032] FIG. 2a illustrates the exemplary second lower layer
subassembly according to embodiments of the invention. FIG. 2a
shows bottom glass or motherglass 216, which can be a large sheet
(e.g. 2.times.3 feet), and from which a number of individual
substrates may be generated. Substantially clear overcoat 218 of
silicon dioxide or polymer can then be applied over bottom glass
216 to prepare the surface for ITO. ITO 220 having a resistivity of
10 ohms per square and an optical index of 1.8 can then be
sputtered over clear overcoat 218. ITO 220 can then be patterned
using photolithography. Compressible spacers or spheres 222 of
10.+-.2 micron height can then be sprayed on. Spacers 200 can have
a compression of 2 microns when the total assembly can be loaded
with 100 grams and can have an optical index that matches the ITO
and/or fluid around them. Unlike the exemplary first lower layer
subassembly, no border spacers are used, and instead border sealing
adhesive 224 can then be printed. Note that adhesive 224 is not
immediately UV-cured so it can be used as an adhesive. Conductive
vias 226 that can have a diameter of 500 microns and a resistivity
of 10 ohms maximum can then be deposited between border sealing
adhesive 224 using a silk-screening process or a robot needle
dispenser. Vias 226 can be made of conductive epoxy or ink and can
provide electrical connections between the top and bottom glass.
Vias 226 can also allow the consolidation of all connections onto a
single layer.
[0033] The first exemplary upper layer subassembly and the second
exemplary lower layer subassembly can then be bonded together, and
scribed and cut to remove excess material. An IC and/or FPC can
then be bonded to the first exemplary upper layer subassembly,
encapsulated, scribed and cut again to remove further excess
material, and edge finished to form an exemplary second touch
sensor panel assembly. The exemplary second touch sensor panel
assembly can then be laminated to an LCD module. All of these steps
can be performed as described above with regard to the exemplary
first touchscreen.
[0034] FIG. 2b shows the exemplary second touch panel assembly that
can be laminated to an LCD module with substantially optically
clear adhesive 248 to form the exemplary second touchscreen. The
view shown is along the short edge of the second exemplary
touchscreen, as shown in the thumbnail. Note that FPC 236 was
folded back at an angle prior to encapsulation in this
embodiment.
[0035] FIG. 2c shows a side detail of the exemplary second
touchscreen assembly, including metal traces 212 in the border
areas. Note fluid 230 in fluid-tight gap 299. The view has changed
to along the long edge of the second exemplary touchscreen, as
shown in the thumbnail.
[0036] FIGS. 3a through 3e illustrate an exemplary third
touchscreen that can be formed by combining the exemplary first
upper layer subassembly, an exemplary third lower layer
subassembly, and the exemplary LCD module according to one
embodiment of this invention. The exemplary third touchscreen of
FIGS. 3a through 3e can also include force-sensitive touch
screens.
[0037] FIGS. 3a through 3c illustrate the exemplary third lower
layer subassembly according to embodiments of the invention. FIG.
3a shows bottom glass or motherglass 316, which can be a large
sheet (e.g. 2.times.3 feet), and from which a number of individual
substrates may be generated. Substantially clear overcoat 318 of
silicon dioxide or polymer can then be applied over bottom glass
316 to prepare the surface for ITO. ITO 320 having a resistivity of
10 ohms per square and an optical index of 1.8 can then be
sputtered over clear overcoat 318. ITO 320 can then be patterned
using photolithography. A bottom shield of ITO 305 at a thickness
of 100 to 1000 ohms per square, for example, can be applied to the
bottom of bottom glass 316 to prevent LCD noise from corrupting the
sensor panel. A mask of photoresist 307 can then be applied over
bottom shield 300 to protect border areas of the touch screen from
anti-reflective (AR) coating. AR coating 331 having an optical
index that can be matched to that of the lamination adhesive or
air, depending on the final attachment method to the LCD, can then
be applied over photoresist 307 and bottom shield 305.
[0038] FIG. 3b shows the step of removing mask 307 and exposing
shield 305 so that conductive tape can be subsequently be adhered
to the shield layer. Spacers, border sealing adhesive, and
conductive vias can then be applied to the exemplary third lower
layer subassembly. The exemplary first upper layer subassembly and
the exemplary third lower layer subassembly can then be bonded
together, and scribed and cut to remove excess material.
[0039] FIG. 3c shows the exemplary first upper layer subassembly
and the exemplary third lower layer subassembly that can be bonded
together to form an exemplary third touch sensor panel assembly.
The view shown is along the short edge of the exemplary third touch
sensor panel assembly, as shown in the thumbnail. Clear optical
fluid 330 can be used to fill in the fluid-tight gap 399 between
the top and bottom layer sub assemblies. Fluid 330 can have
dielectric properties which can enable the row and column traces
formed in ITO layers 320 and 308 to experience a mutual capacitance
between them at crossover points and act as touch sensors. If
force-sensing is employed, the change in the distance between ITO
layers 320 and 308 during a touch can change the mutual capacitance
experienced by each of the touch sensors, effectively representing
a measure of force. IC 332 and FPC 336 can then be bonded to the
first exemplary upper layer subassembly, and conductive tape 333
can be adhered to shield 305 and FPC 336 to ground the bottom
shield 305 to FPC 306. IC 332, FPC 336 and conductive tape 333 can
then encapsulated, and the exemplary first upper layer subassembly
can then be scribed and cut again to remove further excess
material, and can be edge finished to form the exemplary third
touch sensor panel assembly. The exemplary third touch sensor panel
assembly can then be laminated to the exemplary LCD module. All of
these steps can be performed as described above.
[0040] FIG. 3ab shows the exemplary third sensor panel assembly
that can be laminated to the exemplary LCD module to form the
exemplary third touchscreen. Note that FPC 336 was folded back at
an angle in this embodiment.
[0041] FIG. 3d shows a side detail of the exemplary third
touchscreen, including metal traces 312 in the border areas. The
view has changed to along the long edge of the third exemplary
touchscreen, as shown in the thumbnail.
[0042] FIGS. 4a through 4j illustrate an exemplary fourth
touchscreen that can be formed by an exemplary second upper layer
subassembly and the exemplary LCD module according to one
embodiment of this invention.
[0043] FIGS. 4a through 4h illustrate the exemplary second upper
layer subassembly according to embodiments of the invention. FIG.
4a shows top glass or motherglass 400, which can be a large sheet
(e.g. 2.times.3 feet), and from which a number of individual
substrates may be generated. A chemical strengthening step can be
performed on the top glass, which can involve applying a nitric
acid bath at high heat to glass 400, resulting in compressive
forces or stresses in the surface layer of the glass and tensile
stresses in the interior core of the glass that can make the
surface of the glass less likely to crack apart. Anti-glare coating
402 can then be deposited on glass 400. Anti-glare coating 402 can
be particle-embedded silicon dioxide. Alternatively, AR coating or
no coating can also be used. Black mask 404 can be applied to
selected regions of glass 400. Black mask 404 can be applied using
printing techniques, roller coating, or sputtering followed by
etching of unwanted areas, or by using photoimagable polymer. Or
photoimagable polymer. Next, clear overcoat 406 can be applied over
black mask 404 and glass 400. Clear overcoat 406 can be a clear
polymer curable with ultraviolet (UV) light that smoothes over the
step between the black mask and non-black mask areas, and can form
a substantially planar surface for subsequent Indium Tin Oxide
(ITO) sputtering and metal patterning. ITO 408 of 10 to 200 ohms
per square (max) and an optical index of n=1.8 can then be
sputtered over clear overcoat 406, although thicker layers of ITO
can reduce this resistance and thinner layers can increase this
resistance. ITO 408 can then be patterned. Insulator 409 can then
be applied over patterned ITO 408. Insulator 409 can have a
dielectric constant K<4.0 and a thickness of between 10 and 25
microns. Insulator 409 can be applied so that a second layer of ITO
can be added. Photoresist 411 can then be applied to insulator 409
and patterned for subsequent formation of vias 413.
[0044] FIG. 4b shows the etching of insulator 409 using vias 413 in
photoresist 411.
[0045] FIG. 4c shows the step of removing photoresist 411.
[0046] FIG. 4d shows the masking of the center region using
photoresist 410 to protect it from metal sputtering, and the
sputtering of metal 412 over insulator 409 and photoresist 410, and
into via 413 for connecting to traces in first ITO layer 408.
[0047] FIG. 4e shows the removal of photoresist 410.
[0048] FIG. 4f shows the sputtering a second ITO layer 415 of 10
ohms per square and an optical index of 1.8 over metal 412 and
insulator 409, and the patterning of the second ITO layer 415 and
metal 412 using standard lithography processes to create row or
column traces. The simultaneous patterning of the metal and the ITO
layer can be done with a photoresist, a single photo-exposure and
one or two etching steps (ITO and metal have different ideal
etchants). Insulator 409 can have dielectric properties which
enable the row and column traces formed in ITO layers 415 and 408
to experience a mutual capacitance between them at crossover points
and act as touch sensors. Top glass 400 can then be scribed and
separated into individual parts.
[0049] FIG. 4g shows IC 432 that can be bonded to the second layer
of ITO 415 using ACF 434, and FPC 436 that can be bonded to the
second layer of ITO using ACF 438. The view shown is along the
short edge of the exemplary second upper layer subassembly, as
shown in the thumbnail.
[0050] FIG. 4h shows encapsulent 442 formed around IC 432 and FPC
436 to lock them in place. The second upper layer subassembly can
then be scribed and separated to form individual parts, and the
final edges can be shaped, finished and cleaned using grinding and
polishing techniques, as described above.
[0051] FIG. 4i shows the lamination of the exemplary second upper
layer subassembly to exemplary LCD module 419 using optically clear
adhesive 448 to form the exemplary fourth touchscreen. In FIG. 4i,
LCD module 419 can include LCD polarizer 421 with conductive
anti-reflective (AR) coating 423 on its top surface to serve as a
shield for the touch panel.
[0052] FIG. 4j shows an alternative method of laminating LCD module
419 to the exemplary second upper layer assembly by leaving air gap
425 between the two. In FIG. 4z, substantially transparent PET film
427 with a conductive anti-reflective bottom 429 can be applied to
the top glass assembly to provide the shielding for the touch
panel. The anti-reflective coating 429 can be formed from
alternating layers of ITO and titanium dioxide or the like.
[0053] It should be noted that the exemplary upper layer
subassemblies of FIGS. 1-4 can act as both a cover and as a
substrate for the formation of the sensor panel.
[0054] FIGS. 5a through 5d illustrate an exemplary fifth
touchscreen that can be formed by an exemplary third upper layer
subassembly and the exemplary LCD module according to one
embodiment of this invention.
[0055] FIGS. 5a through 5c illustrate an exemplary third upper
layer subassembly according to embodiments of the invention, in
which a touch sensor panel can be formed by forming row and column
traces on the same side of a single top glass substrate. FIG. 5a
shows a finished soda-lime top glass 500, showing two layers on the
top of top glass 500 and a shield on the bottom of the top glass.
In particular, ITO 566 can be formed on the top of top glass 500
and patterned to form column traces. Sol-Gel 560 of 0.025 thickness
and an optical index similar to that of ITO 566 can then be formed
on ITO 566 and patterned to form vias 572. Vias 572 can be filled
with a conductive material. Metal 570 can then be formed and
patterned over Sol-Gel 560 to form traces along the borders of the
subassembly. A second layer of ITO 568 can then be formed and
patterned over metal 570 and Sol-Gel 560 to form row traces.
Sol-Gel 560 can have dielectric properties which can enable the row
and column traces formed in ITO layers 566 and 568 to experience a
mutual capacitance between them at crossover points and act as
touch sensors. ITO rows and columns 566 and 568 can have a
resistivity of 10 to 200 ohms per square and are formed as 0.030
lines and spaces. Metal 570 can have a resistivity of 0.2 ohms per
square and formed as 0.030 lines and spaces. Vias 572 connect metal
traces 570 to the bottom ITO 566.
[0056] Bottom ITO layer 562 having a resistivity of 500 ohms per
square can then be applied to the bottom of top glass 500, and then
covered by temporary protective film 564. ITO 562 can act a shield
for the sensing columns. Note that the exemplary third upper layer
subassembly of FIG. 5b can require an additional cover (not shown).
The exemplary third upper layer subassembly can then be scribed and
cut into individual parts.
[0057] FIG. 5b shows top glass 500 after it has been scribed and
broken into individual parts, with dashed line 574 symbolically
representing the two ITO layers on top of the top glass and
separated by the Sol-Gel dielectric. In FIG. 5d, FPC 576 can be
attached using ACF 586, and IC 532 can be bonded to FPC 576 instead
of directly to the traces on the substrate, because IC 532 would
interfere with the ability of the glass assembly to be
flush-mounted to a cover.
[0058] FIG. 5c shows the step of removing protective layer 564, and
grounding the bottom side ITO 562 using conductive tape 578 for
shielding LCD noise.
[0059] FIG. 5d shows the exemplary third upper layer subassembly
that can be bonded to LCD module 519 using optically clear PSA 580,
and cover 582 that can be bonded to the exemplary third upper layer
subassembly using optically clear adhesive 584, which should be
thicker (e.g. 0.100) then the FPC attached to the top of glass.
[0060] A number of different computing systems can be operable with
the touchscreen stackups described above according to embodiments
of this invention. A touchscreen, which can include a sensor panel
and a display device (e.g. an LCD module), can be connected to
other components in the computing system through connectors
integrally formed on the sensor panel, or using flex circuits. The
computing system can include one or more panel processors and
peripherals, and a panel subsystem. The one or more processors can
include, for example, ARM968 processors or other processors with
similar functionality and capabilities. However, in other
embodiments, the panel processor functionality can be implemented
instead by dedicated logic such as a state machine. Peripherals can
include, but are not limited to, random access memory (RAM) or
other types of memory or storage, watchdog timers and the like.
[0061] The panel subsystem can include, but is not limited to, one
or more analog channels, channel scan logic and driver logic. The
channel scan logic can access RAM, autonomously read data from the
analog channels and provide control for the analog channels. This
control can include multiplexing columns of the multi-touch panel
to analog channels. In addition, channel scan logic can control the
driver logic and stimulation signals being selectively applied to
rows of the multi-touch panel. In some embodiments, the panel
subsystem, panel processor and peripherals can be integrated into a
single application specific integrated circuit (ASIC).
[0062] Driver logic can provide multiple panel subsystem outputs
and can present a proprietary interface that drives a high voltage
driver. The high voltage driver can provide level shifting from a
low voltage level (e.g. complementary metal oxide semiconductor
(CMOS) levels) to a higher voltage level, which can provide a
better signal-to-noise (S/N) ratio for noise reduction purposes.
Panel subsystem outputs can be sent to a decoder and a level
shifter/driver, which can selectively connect one or more high
voltage driver outputs to one or more panel row inputs through a
proprietary interface and can enable the use of fewer high voltage
driver circuits in the high voltage driver. Each panel row input
can drive one or more rows in a multi-touch panel. In some
embodiments, the high voltage driver and decoder can be integrated
into a single ASIC. However, in other embodiments the high voltage
driver and decoder can be integrated into the driver logic, and in
still other embodiments the high voltage driver and decoder can be
eliminated entirely.
[0063] The computing system can also include a host processor for
receiving outputs from the panel processor and performing actions
based on the outputs that can include, but are not limited to,
moving an object such as a cursor or pointer, scrolling or panning,
adjusting control settings, opening a file or document, viewing a
menu, making a selection, executing instructions, operating a
peripheral device connected to the host device, answering a
telephone call, placing a telephone call, terminating a telephone
call, changing the volume or audio settings, storing information
related to telephone communications such as addresses, frequently
dialed numbers, received calls, missed calls, logging onto a
computer or a computer network, permitting authorized individuals
access to restricted areas of the computer or computer network,
loading a user profile associated with a user's preferred
arrangement of the computer desktop, permitting access to web
content, launching a particular program, encrypting or decoding a
message, and/or the like. The host processor can also perform
additional functions that may not be related to panel processing,
and can be coupled to program storage and a display device such as
an LCD for providing a user interface (UI) to a user of the
device.
[0064] As mentioned above, the multi-touch panel can in some
embodiments include a capacitive sensing medium having a plurality
of row traces or driving lines and a plurality of column traces or
sensing lines separated by a dielectric. In some embodiments, the
dielectric material can be transparent, such as PET or glass. The
row and column traces can be formed from a transparent conductive
medium such as ITO or antimony tin oxide (ATO), although other
non-transparent materials such as copper can also be used. In some
embodiments, the row and column traces can be perpendicular to each
other, although in other embodiments other non-orthogonal
orientations are possible. For example, in a polar coordinate
system, the sensing lines can be concentric circles and the driving
lines can be radially extending lines (or vice versa). It should be
understood, therefore, that the terms "row" and "column," "first
dimension" and "second dimensions" or "first axis" and "second
axis" as may be used herein are intended to encompass not only
orthogonal grids, but the intersecting traces of other geometric
configurations having first and second dimensions (e.g. the
concentric and radial lines of a polar-coordinate arrangement).
[0065] At the "intersections" of the traces, where the traces pass
above and below each other (but do not make direct electrical
contact with each other), the traces essentially form two
electrodes. Each intersection of row and column traces can
represent a capacitive sensing node and can be viewed as a picture
element (pixel), which can be particularly useful when the
multi-touch panel is viewed as capturing an "image" of touch. (In
other words, after the panel subsystem has determined whether a
touch event has been detected at each touch sensor in the
multi-touch panel, the pattern of touch sensors in the multi-touch
panel at which a touch event occurred can be viewed as an "image"
of touch (e.g. a pattern of fingers touching the panel).) When the
two electrodes are at different potentials, each pixel can have an
inherent self or mutual capacitance formed between the row and
column electrodes of the pixel. If an AC signal is applied to one
of the electrodes, such as by exciting the row electrode with an AC
voltage at a particular frequency, an electric field and an AC or
signal capacitance can be formed between the electrodes, referred
to as Csig. The presence of a finger or other object near or on the
multi-touch panel can be detected by measuring changes to Csig. The
columns of the multi-touch panel can drive one or more analog
channels in the panel subsystem. In some embodiments, each column
can be coupled to one dedicated analog channel. However, in other
embodiments, the columns can be couplable via an analog switch to a
fewer number of analog channels.
[0066] The touchscreen stackups described above can be
advantageously used in the computing system to provide a
space-efficient touch sensor panel and UI.
[0067] A number of different mobile telephones can include the
touchscreen stackups and computing system described above according
to embodiments of the invention. PSA can be used to bond the sensor
panel to a display device (e.g. LCD module). A number of different
digital audio/video players can also include the touchscreen
stackups and computing system described above according to
embodiments of the invention. These mobile telephones and digital
audio/video players can advantageously benefit from the touchscreen
stackups described above because the touchscreen stackups allow
these devices to be smaller and less expensive, which can be
important consumer factors that can have a significant effect on
consumer desirability and commercial success.
[0068] Although the present invention has been fully described in
connection with embodiments thereof with reference to the
accompanying drawings, it is to be noted that various changes and
modifications will become apparent to those skilled in the art.
Such changes and modifications are to be understood as being
included within the scope of the present invention as defined by
the appended claims.
* * * * *