U.S. patent application number 15/867297 was filed with the patent office on 2018-06-07 for transparent force sensitive structures in an electronic device.
The applicant listed for this patent is Apple Inc.. Invention is credited to James E. Pedder, John Stephen Smith, Michael Vosgueritchian, Xiaonan Wen.
Application Number | 20180157363 15/867297 |
Document ID | / |
Family ID | 58407177 |
Filed Date | 2018-06-07 |
United States Patent
Application |
20180157363 |
Kind Code |
A1 |
Vosgueritchian; Michael ; et
al. |
June 7, 2018 |
Transparent Force Sensitive Structures in an Electronic Device
Abstract
One or more transparent transistor force sensitive structures
can be included in an electronic device. The transistor force
sensitive structures(s) is used to detect a force that is applied
to the electronic device, to a component in the electronic device,
and/or to an input region of the electronic device. As one example,
the one or more transparent transistor force sensitive structures
may be included in a display stack of a display in an electronic
device.
Inventors: |
Vosgueritchian; Michael;
(San Francisco, CA) ; Pedder; James E.; (Thame,
GB) ; Smith; John Stephen; (San Jose, CA) ;
Wen; Xiaonan; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
|
|
Family ID: |
58407177 |
Appl. No.: |
15/867297 |
Filed: |
January 10, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15005256 |
Jan 25, 2016 |
9886118 |
|
|
15867297 |
|
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62235238 |
Sep 30, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 3/0412 20130101;
G06F 3/0416 20130101; G06F 2203/04103 20130101; H01L 27/1218
20130101; G06F 3/0414 20130101; Y10S 977/762 20130101 |
International
Class: |
G06F 3/041 20060101
G06F003/041; H01L 27/12 20060101 H01L027/12 |
Claims
1-6. (canceled)
7. An electronic device, comprising: a cover layer configured to
receive a touch input; a display layer positioned below the cover
layer; a transparent force layer positioned below the cover layer
and configured to detect strain based on the touch input, the
transparent force layer comprising: a first plurality of
transparent piezotronic transistor force sensitive structures
positioned over a first surface of a transparent substrate; and a
processing device configured to receive strain signals from the
first plurality of transparent piezotronic transistor force
sensitive structures and configured to estimate an amount of force
associated with the touch input.
8. The electronic device of claim 7, further comprising a second
plurality of transparent piezotronic transistor force sensitive
structures positioned over a second surface of the transparent
substrate.
9. The electronic device of claim 7, wherein the display layer is
positioned over the transparent force layer.
10. The electronic device of claim 7, wherein the display layer is
positioned below the transparent force layer.
11. The electronic device of claim 7, wherein at least one
transparent piezotronic transistor force sensitive structure
comprises: a first electrode layer positioned between a protective
layer and a first dielectric layer; a semiconducting layer
positioned between the first dielectric layer and a second
dielectric layer; and a second electrode layer positioned between
the second dielectric layer and the transparent substrate.
12. The electronic device of claim 11, wherein the semiconducting
layer comprises one of: a layer comprising zinc oxide; and a layer
of silver nanowires.
13. The electronic device of claim 11, wherein the first and second
electrode layers each comprise a layer of indium tin oxide.
14-40. (canceled)
41. An electronic device, comprising: a force-sensitive structure
comprising: a source electrode; a semiconducting layer positioned
below the source electrode; and a drain electrode positioned below
the semiconducting layer; and a processing circuitry coupled to the
source electrode and the drain electrode of the force-sensitive
structure and configured to estimate an amount of force applied to
the force-sensitive structure based on a current flowing between
the source electrode and the drain electrode of the force-sensitive
structure.
42. The electronic device of claim 41, wherein the semiconducting
layer is formed from a piezoelectric material.
43. The electronic device of claim 41, wherein the current flows
from the source electrode to the drain electrode.
44. The electronic device of claim 41, further comprising a
Schottky contact defined by an interface between the source
electrode and the semiconducting layer.
45. The electronic device of claim 44, wherein: the Schottky
contact is a first Schottky contact; the interface is a first
interface; and the electronic device further comprises a second
Schottky contact defined by a second interface between the drain
electrode and the semiconducting layer.
46. The electronic device of claim 41, further comprising a
substrate; wherein the force-sensitive structure is formed onto the
substrate.
47. The electronic device of claim 46, further comprising: an array
of independent force-sensitive structures defined on the substrate,
the array comprising the force-sensitive structure; wherein each of
the independent force sensitive structures of the array are coupled
to the processing circuitry.
48. The electronic device of claim 46, wherein; the drain electrode
is formed onto and coupled to the substrate; the semiconducting
layer is formed onto and coupled to the drain electrode; and the
source electrode is formed onto and coupled to the semiconducting
layer.
49. The electronic device of claim 41, wherein the drain electrode,
the semiconducting layer, and the source electrode are each formed
from a transparent material.
50. An electronic device, comprising: a display; a transparent
substrate above the display; a transparent array of force-sensitive
structures defined on the transparent substrate, each
force-sensitive structure of the transparent array comprising a
source electrode and a drain electrode disposed on opposite sides
of a piezoelectric semiconductor; and a sense circuitry coupled to
the transparent array and configured to: measure change in current
flowing between the source electrode and the drain electrode of at
least one force-sensitive structure of the transparent array; and
correlate the measured change in current to a strain induced in the
transparent substrate as a result of a force applied to the
transparent substrate.
50. The electronic device of claim 50, wherein each force-sensitive
structure of the transparent array has a rectilinear shape.
51. The electronic device of claim 50, wherein the transparent
substrate is formed from glass.
52. The electronic device of claim 50, wherein the transparent
substrate is coupled to the display.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit under 35 U.S.C. .sctn.
119(e) of U.S. Provisional Patent Application No. 62/235,238, filed
on Sep. 30, 2015, and entitled "Transparent Force Sensitive
Structures in an Electronic Device," which is incorporated by
reference as if fully disclosed herein.
FIELD
[0002] Embodiments described herein generally relate to electronic
devices. More particularly, the present embodiments relate to one
or more transparent force sensitive structures in an electronic
device.
BACKGROUND
[0003] Strain gauges are used to detect or measure strain on an
object. Typically, the electrical resistance of a conventional
strain gauge varies in proportion to the compression and tension
forces it is experiencing. The gauge factor of the strain gauge
represents the sensitivity of the material to strain. In other
words, the gauge factor indicates how much the resistance of the
strain gauge changes with strain. The higher the gauge factor, the
larger the change in resistance. Higher gauge factors allow a
greater range of strain to be detected and measured.
[0004] In some situations, it is desirable for a strain gauge to be
made of a transparent material. For example, transparent strain
gauges may be used when the strain gauges are located in an area
where the strain gauges can be detected visually by a user (e.g.,
though a display). However, some of the materials that can be used
to form a transparent strain gauge create a transparent strain
gauge that has an undesirably low gauge factor.
SUMMARY
[0005] One or more optically transparent transistor force sensitive
structures can be included in an electronic device. As used herein,
the terms "optically transparent" and "transparent" are defined
broadly to include a material that is transparent, translucent, or
not visually discernible by the human eye. The one or more
transistor force sensitive structures can each include a thin-film
transistor force sensitive structure. In one embodiment, a gate
signal is applied to a gate electrode of the transparent transistor
force sensitive structures(s) to adjust the gauge factor of the
transistor force sensitive structures (s). In another embodiment, a
transistor force sensitive structures includes a transparent
piezotronic transistor force sensitive structures that utilizes the
piezo-polarization charges at an interface between a semiconducting
layer and one or more conductive electrodes to control the
transport of charge carriers across the contact barrier.
[0006] The one or more transparent transistor force sensitive
structures are used to detect a force that is applied to the
electronic device, to a component in the electronic device, such as
an input button, and/or to an input region or surface of the
electronic device. In one non-limiting example, a force sensor that
includes one or more optically transparent transistor force
sensitive structures may be incorporated into a display stack of an
electronic device. In some embodiments, the one or more transparent
force sensitive structures are located in an area of the display
stack that is associated with the viewable area of the display. As
such, the force sensitive structures are transparent so a user is
not able (or is less able) to detect the force sensitive structures
when the user is viewing the display.
[0007] In one aspect, an electronic device includes a cover layer
configured to receive at least one touch input, a display layer
positioned below the cover layer, and a force layer positioned
below the cover layer. In one embodiment, the display layer is
positioned between the cover layer and the force layer. In another
embodiment, the force layer is positioned between the cover layer
and the display layer. The force layer is configured to detect
strain based on the at least one force input. The force layer may
include a first plurality of transparent transistor force sensitive
structures positioned over a first surface of a transparent
substrate and at least one first gate contact electrically
connected to each transparent transistor force sensitive structure
in the first plurality of transparent transistor force sensitive
structures. The at least one first gate contact is configured to
receive a first gate signal to adjust a gauge factor of at least
one transistor force sensitive structure in the first plurality of
transparent transistor force sensitive structures. A processing
device is configured to receive strain signals from the first
plurality of transparent transistor force sensitive structures and
configured to estimate an amount of force associated with each
touch input.
[0008] In another aspect, the transparent force layer can include a
first plurality of transparent piezotronic transistor force
sensitive structures positioned over a first surface of a
transparent substrate. A processing device is configured to receive
strain signals from the first plurality of transparent piezotronic
transistor force sensitive structures and configured to estimate an
amount of force associated with each touch input.
[0009] In another aspect, the transparent force layer may include
one or more transparent transistor force sensitive structures that
each include a first gate electrode positioned over a first
semiconducting layer, a first source electrode at least partially
positioned on a surface of the first semiconducting layer below the
first gate electrode, a first drain electrode at least partially
positioned on the surface of the first semiconducting layer below
the first gate electrode, a first strain signal line connected to
the source electrode, and a second strain signal line connected to
the drain electrode. A first gate contact is electrically connected
to the first gate electrode in at least one transparent transistor
force sensitive structure. The first gate contact is configured to
receive a first gate signal to adjust a gauge factor of the at
least one transparent transistor force sensitive structure.
[0010] In yet another aspect, a method for producing an electronic
device can include providing a display layer below the cover layer,
and providing a force layer below the cover layer. The cover layer
is configured to receive at least one touch input, and the force
layer is configured to detect strain based on the at least one
touch input. The force layer may include a first set of transparent
transistor force sensitive structures positioned over a first
surface of a transparent substrate. Each transparent transistor
force sensitive structure includes a conductive electrode
positioned over a transparent semiconducting layer. A processing
device is provided that is configured to receive strain signals
from the first set of transparent transistor force sensitive
structures and configured to estimate an amount of force associated
with each touch input.
[0011] In yet another aspect, a method of operating a transistor
force sensitive structure may include receiving data from one or
more electronic components in an electrical device, determining an
operating state or condition of the electronic device based on the
received data, and adjusting a force threshold based on the
determined operating state or condition. The force threshold is
associated with a force layer that includes at least one
transparent transistor force sensitive structure. An example
electronic component includes, but is not limited to, a motion
sensor, a light sensor, an image sensor, a clock, and an
application program.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The disclosure will be readily understood by the following
detailed description in conjunction with the accompanying drawings,
wherein like reference numerals designate like structural elements,
and in which:
[0013] FIG. 1 shows one example of an electronic device that can
include one or more transparent force sensitive structures;
[0014] FIG. 2 shows a cross-sectional view of the display taken
along line 2-2 in FIG. 1;
[0015] FIG. 3 shows a plan view of an example transparent force
layer that is suitable for use in a display stack;
[0016] FIG. 4 shows an enlarged plan view of the area 306 shown in
FIG. 3;
[0017] FIG. 5 shows a simplified cross-sectional view taken along
line A-A in FIG. 4 of a first transparent force sensitive structure
that is suitable for use in the force layer shown in FIG. 3;
[0018] FIG. 6 shows a simplified cross-sectional view taken along
line A-A in FIG. 4 of a second transparent force sensitive
structure that is suitable for use in the force layer shown in FIG.
3;
[0019] FIG. 7 shows a channel width in a semiconducting layer when
a gate signal is not applied to a gate electrode;
[0020] FIG. 8 shows a channel width in the semiconducting layer
when a gate signal is applied to a gate electrode;
[0021] FIG. 9 shows an example plot depicting the effect of a gate
signal on the channel width and the source drain current;
[0022] FIG. 10 shows a flowchart of a method for operating an
electronic device that includes one or more of the transparent
force sensitive structures shown in FIGS. 5 and 6;
[0023] FIG. 11 shows a simplified cross-sectional view of an
alternate third transparent force sensitive structure that is
suitable for use in the force layer shown in FIG. 3;
[0024] FIG. 12 shows a flowchart of a method for producing an
electronic device that includes one or more transparent force
sensitive structures; and
[0025] FIG. 13 shows a block diagram of an example electronic
device that can include one or more transparent force sensitive
structures.
DETAILED DESCRIPTION
[0026] Reference will now be made in detail to representative
embodiments illustrated in the accompanying drawings. It should be
understood that the following descriptions are not intended to
limit the embodiments to one preferred embodiment. To the contrary,
it is intended to cover alternatives, modifications, and
equivalents as can be included within the spirit and scope of the
described embodiments as defined by the appended claims.
[0027] The following disclosure relates to an electronic device
that includes one or more optically transparent force sensitive
structures configured to detect strain based on an amount of force
applied to the electronic device, a component in the electronic
device, and/or an input region of the electronic device. As one
example, the one or more transparent force sensitive structures can
be incorporated into a display stack of an electronic device and at
least a portion of the top surface of the display screen may be an
input region. In some embodiments, the one or more transparent
force sensitive structures are located in an area of the display
stack that is associated with the viewable area of the display. As
such, the force sensitive structures are transparent so a user is
not able (or is less able) to detect the force sensitive structures
when the user is viewing the display. As used herein, the terms
"optically transparent" and "transparent" are defined broadly to
include a material that is transparent, translucent, or not visibly
discernible by the human eye.
[0028] The one or more optically transparent force sensitive
structures can each include a thin film transistor force sensitive
structure. In some embodiments, the gauge factor of a transistor
force sensitive structure is a function of the free carrier
concentration or mobility in an optically transparent thin film
semiconducting layer. Low carrier concentration can produce a
higher gauge factor in a transistor force sensitive structure. A
gate signal is applied to a gate electrode of the transistor force
sensitive structure to alter the number of free carriers in the
semiconducting layer. For example, the gate signal may deplete the
semiconducting layer of free carriers, which effectively increases
the gauge factor of the transistor force sensitive structure.
[0029] In other embodiments, the transistor force sensitive
structure(s) is a piezotronic transistor force sensitive structure
that utilizes the piezo-polarization charges at an interface
between a semiconducting layer and a conductive electrode to
control the transport of charge carriers across contact barriers.
In particular, the interfaces between a semiconducting layer and
two conductive electrodes each form a Schottky contact or barrier
to charge injection and collection. The barriers are dependent on
the energetics of both the semiconducting layer and the two
electrodes. Since the material in the semiconducting layer is
piezoelectric, an electric potential ("piezopotential") is produced
in the semiconducting layer as the force or applied strain on the
semiconducting layer changes. This piezopotential results from the
polarization of the non-mobile charge carriers in the
semiconducting layer. The charge carrier transport process across
the Schottky barrier can be controlled by the changes in
polarization.
[0030] In a piezotronic transistor force sensitive structure, the
conductive electrodes are positioned on the polar surfaces of the
semiconducting layer. During a compressive strain, negative charges
are induced at an interface between the semiconducting layer and a
source electrode (at one polar surface of the semiconducting layer)
and positive charges are induced at the interface between the
semiconducting layer and a drain electrode (the other polar surface
of the semiconducting layer). The negative charges increase the
barrier height, making it harder to inject carriers into the
semiconducting layer. In a transistor architecture, the increased
barrier height translates to a decrease in the source-drain
current. Conversely, during a tensile strain the polarities of the
induced charges switch, which decreases the barrier height. In a
transistor architecture, the lower barrier height translates to an
increase in the source-drain current. The change in the
source-drain current is measured and correlated to an amount of
strain.
[0031] Directional terminology, such as "top", "bottom", "front",
"back", "leading", "trailing", etc., is used with reference to the
orientation of the Figure(s) being described. Because components of
embodiments described herein can be positioned in a number of
different orientations, the directional terminology is used for
purposes of illustration only and is in no way limiting. When used
in conjunction with layers of a display or device, the directional
terminology is intended to be construed broadly, and therefore
should not be interpreted to preclude the presence of one or more
intervening layers or other intervening features or elements. Thus,
a given layer that is described as being formed, positioned,
disposed on or over another layer, or that is described as being
formed, positioned, disposed below or under another layer may be
separated from the latter layer by one or more additional layers or
elements.
[0032] These and other embodiments are discussed below with
reference to FIGS. 1-13. However, those skilled in the art will
readily appreciate that the detailed description given herein with
respect to these Figures is for explanatory purposes only and
should not be construed as limiting.
[0033] FIG. 1 shows one example of an electronic device that can
include one or more transparent force sensitive structures. In the
illustrated embodiment, the electronic device 100 is implemented as
a smart telephone. Other embodiments can implement the electronic
device differently. For example, an electronic device can be a
laptop computer, a tablet computing device, a wearable computing
device such as a smart watch or a health assistant, a digital music
player, a display input device, a remote control device, and other
types of electronic devices that include a force sensitive
structure or structures.
[0034] The electronic device 100 includes an enclosure 102
surrounding a display 104 and one or more input/output (I/O)
devices 106 (shown as button). The enclosure 102 can form an outer
surface or partial outer surface for the internal components of the
electronic device 100, and may at least partially surround the
display 104. The enclosure 102 can be formed of one or more
components operably connected together, such as a front piece and a
back piece. Alternatively, the enclosure 102 can be formed of a
single piece operably connected to the display 104.
[0035] The display 104 can provide a visual output for the
electronic device 100 and/or function to receive user inputs to the
electronic device. For example, the display 104 can be a
multi-touch capacitive sensing touchscreen that can detect one or
more user touch and/or force inputs. The display 104 may be
substantially any size and may be positioned substantially anywhere
on the electronic device 100. The display 104 can be implemented
with any suitable display, including, but not limited to, a
multi-touch sensing touchscreen device that uses liquid crystal
display (LCD) technology, light emitting diode (LED) technology,
organic light-emitting display (OLED) technology, or organic
electro luminescence (OEL) technology.
[0036] In some embodiments, the I/O device 106 can take the form of
a home button, which may be a mechanical button, a soft button
(e.g., a button that does not physically move but still accepts
inputs), an icon or image on a display, and so on. Further, in some
embodiments, the button can be integrated as part of a cover layer
of the electronic device. Although not shown in FIG. 1, the
electronic device 100 can include other types of I/O devices, such
as a microphone, a speaker, a camera, and one or more ports such as
a network communication port and/or a power cord port.
[0037] A cover layer 108 may be positioned over the front surface
of the electronic device 100. One or more portions of the cover
layer 108 can function as an input region and receive touch and/or
force inputs. For example, the portion of the cover layer 108
overlying the display 104 can receive touch and/or force inputs. In
one embodiment, the cover layer 108 may cover the entire front
surface of the electronic device. In another embodiment, the cover
layer 108 can cover the display 104 but not the I/O device 106. In
such embodiments, the I/O device 106 may be positioned in an
opening or aperture formed in the cover layer 108.
[0038] Force sensitive structures can be included in one or more
locations of the electronic device 100. For example, in one
embodiment one or more force sensitive structures may be included
in the I/O device 106. The strain sensor(s) can be used to measure
an amount of force and/or a change in force that is applied to the
I/O device 106. Additionally or alternatively, one or more force
sensitive structures can be positioned under at least a portion of
the enclosure to detect a force and/or a change in force that is
applied to the enclosure. Additionally or alternatively, one or
more force sensitive structures may be included in a display stack
of the display 104. The force sensitive structures(s) can be used
to measure an amount of force and/or a change in force that is
applied to the display or to a portion of the display. FIGS. 2-12
are described in conjunction with a display stack.
[0039] As described earlier, in one non-limiting example the entire
top surface of a display (or the cover layer disposed over the top
surface of the display) may be an input region that is configured
to receive touch and/or force inputs from a user. A force layer
that includes one or more force sensitive structures can be
included in a display stack of a display (e.g., display 104 in FIG.
1). FIG. 2 shows a cross-sectional view of the display taken along
line 2-2 in FIG. 1. The display stack 200 includes a cover layer
201 positioned over a front polarizer 202. The cover layer 201 can
be a flexible touchable surface that is made of any suitable
material, such as, for example, glass, plastic, sapphire, or
combinations thereof. The cover layer 201 can act as an input
region for a touch sensor and/or a force sensor by receiving touch
and force inputs from a user. The user can touch and/or apply force
to the cover layer 201 with one or more fingers or with another
element, such as a stylus.
[0040] An adhesive layer 204 can be disposed between the cover
layer 201 and the front polarizer 202. Any suitable adhesive can be
used for the adhesive layer, such as, for example, an optically
clear adhesive. A display layer 206 can be positioned below the
front polarizer 202. As described previously, the display layer 206
may take a variety of forms, including a liquid crystal display
(LCD), a light-emitting diode (LED) display, and an organic
light-emitting diode (OLED) display. In some embodiments, the
display layer 206 can be formed from glass or have a glass
substrate. Embodiments described herein include a multi-touch
touchscreen LCD display layer.
[0041] Additionally, the display layer 206 can include one or more
layers. For example, a display layer 206 can include a VCOM buffer
layer, a LCD display layer, and a conductive layer disposed over
and/or under the display layer. In one embodiment, the conductive
layer may comprise an indium tin oxide layer.
[0042] A rear polarizer 208 may be positioned below the display
layer 206, and a force layer 210 below the rear polarizer 208. The
force layer 210 includes a substrate 212 having a first set of
independent transparent force sensitive structures 214 on a first
surface 216 of the substrate 212 and a second set of independent
transparent force sensitive structures 218 on a second surface 220
of the substrate 212. The first and second sets of independent
transparent force sensitive structures can each include one or more
transparent force sensitive structures. In the illustrated
embodiment, the one or more transparent force sensitive structures
are located in an area of the display stack that is associated with
the viewable area of the display. As such, the force sensitive
structures are transparent so a user is not able (or is less able)
to detect the force sensitive structures when the user is viewing
the display. In the illustrated embodiment, the first and second
surfaces 216, 220 are opposing top and bottom surfaces of the
substrate 212, respectively. An adhesive layer 222 may attach the
substrate 212 to the rear polarizer 208.
[0043] A back light unit 224 can be disposed below (e.g., attached
to) the force layer 210. The back light unit 224 may be configured
to support one or more portions of the substrate 212 that do not
include transparent force sensitive structures. For example, as
shown in FIG. 2, the back light unit 224 can support the ends of
the substrate 212. Other embodiments may configure a back light
unit differently.
[0044] The force sensitive structures are typically connected to
sense circuitry 226 through conductive connectors 228. The sense
circuitry 226 is configured to receive a strain signal and/or to
detect changes in a strain signal received from each force
sensitive structure. The strain signals can be correlated to an
amount of force that is applied to the cover layer 201. In some
embodiments, the sense circuitry 226 may also be configured to
provide information about the location of a touch based on the
relative difference in the change of an electrical property of the
transparent force sensitive structures 214, 218. Collectively, the
force layer 210 and the sense circuitry 226 operably connected to
the force sensitive structures form a force sensor in one
embodiment. In other embodiments, a force layer, the sense
circuitry, and a processing device operably connected to the sense
circuitry form a force sensor.
[0045] In the illustrated embodiment, a gap 236 exists between the
force layer 210 and the back light unit 224. Strain measurements
intrinsically measure the force at a point on the first surface 216
of the substrate 212 plus the force from the bottom at that point
on the second surface 220 of the substrate 212. When the gap 236 is
present, there are no forces on the second surface 220. Thus, the
forces on the first surface 216 can be measured independently of
the forces on the second surface 220. In alternate embodiments, the
force layer 210 may be positioned above the display layer 206. For
example, the force layer 210 may be positioned above the display
layer 206 when the display stack 200 does not include the gap
236.
[0046] Other embodiments can configure a force layer differently.
For example, a force layer can include only one set of transparent
force sensitive structures on a surface of the substrate. A
processing device may be configured to determine an amount of
force, or a change in force, applied to an input region based on
signals received from the one set of transparent force sensitive
structures. Additionally or alternatively, the force layer 210 may
be positioned above the display layer 206 in other embodiments.
[0047] FIG. 3 shows a plan view of an example transparent force
layer that is suitable for use in a display stack. The force layer
300 can include a grid of independent optically transparent force
sensitive structures 304 formed in or on a substrate 302. The
transparent force sensitive structures 304 may be formed in or on
at least a portion of one or both surfaces of the substrate 302. In
this example, the transparent force sensitive structures 304 are
formed as an array of rectilinear sensing elements, although other
shapes and array patterns can also be used. The substrate 302 can
be formed of any suitable material or materials. In one embodiment,
the substrate 302 is formed with an optically transparent material,
such as glass, a polymer resin (e.g., polyethylene terephthalate
(PET), or a plastic.
[0048] FIG. 4 shows an enlarged plan view of the area 306 shown in
FIG. 3. An optically transparent conductive gate layer 400 includes
gate electrodes 402 and connecting sections 404. Each gate
electrode 402 is included in a transparent force sensitive
structure 304. The conductive gate layer 400 is electrically
connected to one or more gate contacts 406. A gate signal (e.g.,
voltage) is applied to the conductive gate layer 400 through gate
contact(s) 406. In the illustrated embodiment, each gate electrode
402 receives the gate signal because all of the gate electrodes 402
are electrically connected to each other by connecting sections
404.
[0049] In other embodiments, a force layer can include multiple
gate contacts and individual gate electrodes 402. Each gate contact
406 may be electrically connected to a single gate electrode 402 or
to a group of gate electrodes 402. Alternatively, in some
embodiments a force layer can include multiple gate contacts 406
and distinct groups of gate electrodes 402. The gate electrodes in
each group of gate electrodes may be electrically connected
together by connecting sections. A gate contact 406 may be
electrically connected to each group of gate electrodes 402 in the
force layer.
[0050] Returning to FIG. 4, a first strain signal line 408 and a
second strain signal line 410 electrically connects each force
sensitive structure 304 to first and second source-drain contacts
412, 414, respectively. A bias signal (e.g., voltage) is applied to
the first source-drain contact(s) and a strain signal is received
at the second source-drain contact(s) when a force is applied to an
input region of the electronic device (e.g., the cover layer 108
disposed over the display 104 in FIG. 1). The strain signals are
received by a processing device (not shown) that correlates at
least one strain signal to an amount of force (or a change in
force) applied to the input region of the electronic device.
[0051] In the illustrated embodiment, the force layer 300 includes
a display area 416 and a non-display area 418. The display area 416
is an area of the display stack that is associated with the
viewable section of the display. The non-display area 418 is
associated with an area of the display that does not provide an
output (e.g., image) to the user when the user is viewing the
display. In other words, the display area 416 is in the optical
path of the display and/or back light unit, while the non-display
area 418 is outside of the optical path of the display and/or back
light unit.
[0052] The dashed line 420 illustrates an example boundary between
the display and non-display areas 416, 418 of the force layer 300.
In one embodiment, the transparent force sensitive structures 304
and the strain signal lines 408, 410 are disposed in the display
area 416 and the gate and source-drain contacts 406, 412, 414 are
positioned in the non-display area 418. As such, the transparent
force sensitive structures 304 and the strain signal lines 408, 410
are formed with an optical transparent material or materials. In
some embodiments, the gate and source-drain contacts 406, 412, 414
are also formed with an optically transparent material. However,
when the gate and source-drain contacts 406, 412, 414 are located
in the non-display area 418, the gate and source-drain contacts
406, 412, 414 can be formed with an opaque material or materials,
including, but not limited to, a metal.
[0053] FIG. 5 shows a simplified cross-sectional view taken along
line A-A in FIG. 4 of a first transparent force sensitive structure
that is suitable for use in the force layer shown in FIG. 3. The
transparent force sensitive structure 500 is constructed as an
optically transparent thin-film transistor force sensitive
structure that includes the gate electrode 402. A dielectric layer
502 is positioned below the gate electrode 402. The dielectric
layer 502 can be formed with any suitable dielectric material. One
example dielectric material is silicon dioxide.
[0054] The gauge factor of the transistor force sensitive structure
500 is a function of the free carrier concentration or mobility in
an optically transparent thin film semiconducting layer 504. A low
carrier concentration can produce a higher gauge factor in a
transistor force sensitive structure. A gate signal is applied to
the gate electrode 402 (via gate contact 406 in FIG. 4) to alter
the number of free carriers in the semiconducting layer 504. For
example, the gate signal may deplete the semiconducting layer 504
of free carriers, which effectively increases the gauge factor of
the transistor force sensitive structure. As described earlier, the
gauge factor of a force sensitive structure represents the
sensitivity of the material to strain. The higher the gauge factor,
the larger the change in resistance. A higher gauge factor produces
a force sensitive structure that is more sensitive to strain, which
may allow a greater range of strain to be detected and
measured.
[0055] In the illustrated embodiment, the optically transparent
thin film semiconducting layer 504 is positioned below the
dielectric layer 502 and over the substrate 302. Example
transparent semiconducting materials include, but are not limited
to, silver nanowires or a semiconducting oxide such as indium tin
oxide (ITO) or zinc oxide (ZnO). In the illustrated embodiment, a
first source-drain (S/D) electrode 506 and a second source-drain
(S/D) electrode 508 are positioned on either side of the
semiconducting layer 504 and directly contact at least one surface
of the semiconducting layer 504. In a non-limiting example, the
first S/D electrode 506 is a source electrode and the second S/D
electrode 508 is a drain electrode (or vice versa). Although not
shown in FIG. 5, a strain signal line (e.g., first strain signal
line 408 in FIG. 4) is electrically connected to one S/D electrode
(e.g., S/D electrode 506) and another strain signal line (e.g.,
second strain signal line 410) is electrically connected to the S/D
electrode (e.g., S/D electrode 508).
[0056] Other embodiments can construct the thin-film transistor
force sensitive structure differently. For example, the first and
second source-drain electrodes 506, 508 can be positioned on a
surface of the semiconducting layer 504 within openings formed in
the dielectric layer 502.
[0057] To determine a force measurement, a constant gate signal may
be applied to the gate electrode 402 to produce an electric field
and deplete the semiconducting layer 504 of free carriers, which
can increase the gauge factor of the transistor force sensitive
structure 500. A constant source/drain signal is applied to the
source electrode (e.g., S/D electrode 506), and a strain signal is
received from the drain electrode (e.g., S/D electrode 508). The
strain signal represents an amount of strain imposed on the
transistor force sensitive structure 500. A processing device (not
shown) can receive the strain signal from the transistor force
sensitive structure 500 and correlate the strain signal to the
amount of force applied to an input region (e.g., the cover layer
108 over the display 104 in FIG. 1).
[0058] The semiconducting layer 504 can be formed in any suitable
shape and with any given dimensions. For example, a semiconducting
layer can be formed in a serpentine shape. In other embodiments,
the semiconducting layer can have a different shape and/or
different dimensions. In a non-limiting embodiment, the
semiconducting layer may not be patterned into a given shape.
[0059] FIG. 6 shows a simplified cross-sectional view taken along
line A-A in FIG. 4 of a second transparent force sensitive
structure that is suitable for use in the force layer shown in FIG.
3. The second transparent force sensitive structure 600 is similar
to the thin-film transistor force sensitive structure 500 shown in
FIG. 5, with the addition of a second gate electrode 602. Thus, the
transistor force sensitive structure 600 is a dual gate electrode
transistor force sensitive structure that includes the first gate
electrode 402 and the second gate electrode 602.
[0060] A second dielectric layer 604 is positioned below the first
semiconducting layer 504, and the second gate electrode 602 is
positioned between the second dielectric layer 604 and the
substrate 302. As described earlier, the gauge factor of the
transistor force sensitive structure 600 is a function of the free
carrier concentration or mobility in the semiconducting layer 504.
In some situations, a single gate electrode (e.g., gate electrode
402) may not produce a sufficient electric field to adequately
change the free carrier concentration in the semiconducting layer
504 to produce a given or desired gauge factor (or a particular
range of gauge factors). Thus, in some embodiments the combination
of the first and second gate electrodes 402, 602 may generate
electric fields that adequately deplete the free carrier
concentration in the semiconducting layer 504 and produce a given
or desired gauge factor (or a particular range of gauge
factors).
[0061] The first and second gate electrodes 402, 602 may be formed
with the same material(s) or with different materials. In one
embodiment, the second gate electrode 602 is included in a second
conductive gate layer (not shown) that is similar to the conductive
gate layer 400 in FIG. 4. In other embodiments, the second gate
electrode 602 is a discrete second gate electrode that is not
electrically connected to the second gate electrodes in other force
sensitive structures. Additionally, in some embodiments the first
and second gate electrodes 402, 602 can be electrically connected
to same one or more gate contacts (e.g., gate contact 406 in FIG.
4). In such embodiments, the first and second gate electrodes 402,
602 receive the same gate signal to deplete the semiconducting
layer 504. In other embodiments, the first gate electrode 402 can
be electrically connected to one or more first gate contacts (e.g.,
gate contact 406 in FIG. 4) and the second gate electrode 602 may
be electrically connected to a different one or more second gate
contacts. In such embodiments, the second gate electrode 602 is
able to receive a different gate signal (e.g., different signal
level) than the gate signal received by the first gate electrode
402.
[0062] FIG. 7 shows a channel width in a semiconducting layer when
a gate signal is not applied to a gate electrode. In a
semiconducting layer, a channel comprises a high conductivity
region that connects the source and drain in the transistor. The
channel 700 has a width D1 in the absence of a gate signal. As
shown in FIG. 8, the channel 800 has a different (narrower) channel
width D2 when a gate signal is applied to a gate electrode (e.g.,
gate electrode 402 in FIG. 5). Charge carriers 802 have been
depleted from the semiconducting layer 804, which narrows the
channel width from D1 to D2. Because the gauge factor is a function
of the free carrier concentration (or mobility), the narrowing of
the channel width effectively increases the gauge factor of the
transistor force sensitive structure. The amount of change in the
channel width (D1 to D2) depends on several factors, including the
signal level of the gate signal, the signal level of the bias
signal applied to a source/drain electrode, the material used to
form the semiconducting layer, the dielectric constant of the
dielectric layer, and/or the thickness of the dielectric layer. In
some embodiments, one or more of these factors is chosen to
customize or tune the amount of charge carrier depletion and
produce a given gauge factor or a particular range of gauge
factors.
[0063] FIG. 9 shows example output plots of a transistor force
sensitive structure. As shown in FIG. 9, plot 900 represents the
maximum output current (drain current I.sub.D), which occurs when
the gate voltage is zero. Plots 902, 904, and 906 represent various
signal levels for I.sub.D based on different gate signals. As
shown, I.sub.D decreases as the gate signal becomes more
negative.
[0064] The decrease in I.sub.D is due at least in part to the
narrowing of the conductive channel. The area to the left of line
908 represents the linear region of the transistor force sensitive
structure and the area to the right of line 908 the saturation
region. In the saturation region, the gate signal does not
significantly impact the signal level of I.sub.D, which means the
gate signal does not significantly vary the width of the conductive
channel (e.g., conductive channel has become too narrow). In the
linear region, however, the gate signal has a more significant
impact on the signal level of I.sub.D, which means the gate signal
has a noticeable impact on the width of the conductive channel. By
operating the transistor force sensitive structure in the linear
region, different gate signals can change the gauge factor of the
transistor force sensitive structure. This is because the gauge
factor is a function of the free carrier concentration (or
mobility). When the channel width is wider (e.g., in FIG. 9 when
signal level of I.sub.D is higher based on a less negative gate
signal), fewer free carriers have been depleted so the number of
free carriers is higher, which in turn decreases the gauge factor.
Conversely, when the channel width is narrower (e.g., in FIG. 9
when signal level of I.sub.D is lower based on more negative gate
signal), more free carriers have been depleted so the number of
free carriers is lower, which in turn increases the gauge factor. A
higher gauge factor causes the transistor force sensitive structure
to be more sensitive to strain, even small strains. This allows the
transistor force sensitive structure to detect a greater range of
strain.
[0065] In some embodiments, the operation of the transparent force
sensitive structure(s) shown in FIG. 5 and/or FIG. 6 can be changed
dynamically based on the expected force inputs and/or based on data
from other electronic components in an electronic device, such as
sensors, clocks, and application programs (e.g., a calendar, a
navigation program). For example, the amount of change in the
channel width can be adjusted (e.g., narrowed) dynamically based on
the expected force inputs and/or based on data from other
electronic components in an electronic device. A processing device
can receive data from a motion sensor (e.g., accelerometer,
gyroscope) and determine the electronic device is stationary. The
processing device can adjust the gate signal level that is applied
to the gate layer to a first gate signal level, which can produce a
slightly narrow channel width. With a slightly narrow channel
width, a greater amount of force may be needed in order for the
force input to be recognized by the processing device.
Alternatively, a processing device can receive data from a motion
sensor and determine the electronic device is moving. The
processing device may adjust the gate signal level to a second gate
signal level, which can produce a narrower channel width (more
narrow than the channel width produced with the first gate signal
level). With the narrower channel width, a lesser amount of force
may be needed in order for the force input to be recognized by the
processing device.
[0066] In another example, a processing device can receive data
from a light sensor and determine the electronic device is in a
dark environment. Additionally or alternatively, the processing
device may receive data from a clock to determine the time of day.
The processing device can adjust the gate signal level that is
applied to the gate layer to a first gate signal level, which can
produce a slightly narrow channel width. With a slightly narrow
channel width, a greater amount of force may be needed in order for
the force input to be recognized by the processing device.
[0067] FIG. 10 shows a flowchart of a method for operating an
electronic device that includes one or more of the transparent
force sensitive structures shown in FIGS. 5 and 6. Initially, as
shown in block 1000, data is received from one or more electronic
components in the electronic device. As described earlier, the
electronic component(s) can be a sensor (e.g., accelerometer, light
sensor, image sensor), a clock, and/or an application program
(e.g., calendar, navigation program). An operating state or
condition is then determined based on the data (block 1002). For
example, a processing device may be configured to receive the data
from the electronic component(s) and determine an operating state
or condition based on the data. An example operating state or
condition can include movement, the speed or type of movement, the
time of day (e.g., a time when a user is sleeping or not
interacting with the electronic device), and/or the presence of the
electronic device in a dark or unlit environment.
[0068] Next, as shown in block 1004, a determination is made as to
whether a force threshold is to be adjusted. The force threshold
may be adjusted based on the determined operating state or
condition. The force threshold can be increased, decreased, or
remain the same depending on the operating state or condition. The
method returns to block 1000 when the force threshold will not be
adjusted. Alternatively, the force threshold is adjusted at block
1006 when the force threshold is to be adjusted.
[0069] A touch input is then received at block 1008. When a touch
input is received, a determination is made at block 1010 as to
whether the force applied during the touch input equals or exceeds
the force threshold. A force input is not registered or detected if
the applied force does not equal or exceed the force threshold
(block 1012). The process then returns to block 1000. In some
embodiments, the touch input may be registered or recognized by the
electronic device. A touch input may be a binary input in that a
state of a touch input is only one of two states; a touch input is
recognized or a touch input is not recognized.
[0070] When the touch input includes an applied force that equals
or exceeds the force threshold, the method continues at block 1014
where a force input is registered and an appropriate action is
taken based on the force input. The method then returns to block
1000. Unlike a touch input, a force input is a non-binary input. A
state of a force input can be one of a range of states (e.g., three
or more states). In other words, a force input has a greater range
of potential values compared to a touch input. In some embodiments,
a force sensor can distinguish different forces. In such
embodiments, a force may correspond to a particular action, and two
difference forces can correspond to two different particular
actions.
[0071] Additionally or alternatively, in some embodiments the
transistor force sensitive structures can be operated in different
modes or states based on the gate signal that is applied to the
gate electrodes. When an electronic device includes multiple
transistor force sensitive structures, some of the transistor force
sensitive structures can receive one gate signal while other
transistor force sensitive structures receive another gate signal.
For example, in the embodiment shown in FIG. 2, the first set of
transparent transistor force sensitive structures may receive a
first gate signal while the second set of transparent transistor
force sensitive structures receive a different second gate signal
(e.g., different signal level). Additionally or alternatively, some
of the transistor force sensitive structures in the first set of
transparent transistor force sensitive structures may receive a
first gate signal while other transistor force sensitive structures
in the first set of transparent transistor force sensitive
structures receive a different second gate signal. Additionally or
alternatively, some of the transistor force sensitive structures in
the second set of transparent transistor force sensitive structures
can receive a third gate signal while other transistor force
sensitive structures in the second set of transparent transistor
force sensitive structures receive a different fourth gate
signal.
[0072] FIG. 11 shows a simplified cross-sectional view of an
alternate third transparent force sensitive structure that is
suitable for use in the force layer shown in FIG. 3. The
illustrated piezotronic transistor force sensitive structure 1100
utilizes the piezo-polarization charges at an interface between a
semiconducting layer and a conductive electrode to control the
transport of charge carriers across contact barriers. In the
illustrated embodiment, a protective layer 1102 is positioned over
a first electrode 1104 (e.g., a source electrode). A thin-film
optically transparent semiconducting layer 1106 is positioned below
the first electrode 1104. A second electrode 1108 (e.g., a drain
electrode) is positioned between the semiconducting layer 1106 and
the substrate 302. Although not shown in FIG. 11, the first and the
second strain signal lines can be connected to the first and the
second electrodes 1104, 1108, respectively.
[0073] As described earlier, the interfaces between the
semiconducting layer 1106 and the first and second electrodes 1104,
1108 each forms a Schottky contact or barrier to charge injection
and collection. The barriers are dependent on the energetics of
both the semiconducting layer 1106 and the first and second
electrodes 1104, 1108. Since the material in the semiconducting
layer 1106 is piezoelectric, a piezopotential is produced in the
semiconducting layer 1106 as the force or applied strain on the
semiconducting layer 1106 changes. This piezopotential results from
the polarization of the non-mobile charge carriers in the
semiconducting layer 1106. The charge carrier transport process
across the Schottky barrier can be controlled by the changes in
polarization. For example, during a compressive strain, negative
charges are induced at the interface 1110 between the
semiconducting layer 1106 and the first electrode 1104 and positive
charges are induced at the interface 1112 between the
semiconducting layer 1106 and the second electrode 1108. The
negative charges at the interface 1110 increase the barrier height.
It is harder to inject carriers into the semiconducting layer 1106
with an increased barrier height. In a transistor architecture, the
increased barrier height translates to a decrease in the
source-drain current. Conversely, during a tensile strain, positive
charges are induced at the interface 1110 and negative charges at
the interface 1112. The positive charges at the interface 1110
decrease the barrier height. In a transistor architecture, the
decreased barrier height translates to an increase in the
source-drain current. The change in the source-drain current is
measured and correlated to an amount of strain.
[0074] The first and second electrodes 1104, 1108 can be formed
with any suitable optically transparent conductive material,
including, but not limited to, indium tin oxide. Additionally, the
thin-film optically transparent semiconducting layer 1106 can be
formed with any suitable transparent semiconducting material.
Example transparent semiconducting materials include, but are not
limited to, a thin-film of silver nanowires or a semiconducting
oxide such as zinc oxide. In some situations, the use of a
semiconducting zinc oxide layer provides several advantages. Zinc
oxide has a Poisson's Ratio of approximately 0.25. Zinc oxide has a
high melting point and experiences small thermal expansion.
Additionally, zinc oxide is compatible with micro-fabrication
techniques.
[0075] FIG. 12 shows a flowchart of a method for producing an
electronic device that includes one or more transparent force
sensitive structures. Initially, a display layer and a force layer
are provided below a cover layer (blocks 1200 and 1202). The force
layer can include one or more transparent transistor (FIG. 5 and/or
FIG. 6) and/or piezotronic transistor force sensitive structures
(FIG. 11), along with associated strain signal lines, positioned on
at least one surface of a substrate. As described earlier, in one
embodiment the force layer is positioned below the display layer.
In another embodiment, the force layer may be disposed above the
display layer.
[0076] In embodiments that include one or more transparent
transistor force sensitive structures as shown in FIGS. 5 and 6, at
least one gate contact that is electrically connected to the one or
more transparent force sensitive structures is provided at block
1204. Block 1204 is optional and is omitted in embodiments that do
not include the transparent force sensitive structures illustrated
in FIGS. 5 and 6.
[0077] Next, as shown in block 1206, a processing device is
provided. The processing device is operably connected to the one or
more transparent force sensitive structures. The processing device
is configured to receive a strain signal from at least one
transparent force sensitive structure and correlate the strain
signal(s) to an amount of force.
[0078] FIG. 13 shows an illustrative block diagram of an electronic
device that can include one or more transparent force sensitive
structures. As discussed earlier, one or more transparent force
sensitive structures can be located on a variety of components
and/or at one or more different locations in an electronic device
to detect a force applied on the component or on the electronic
device. The illustrated electronic device 1300 can include one or
more processing devices 1302, memory 1304, one or more input/output
(I/O) devices 1306, a power source 1308, one or more sensors 1310,
a network communication interface 1312, and a display 1314, each of
which will be discussed in more detail.
[0079] The one or more processing devices 1302 can control some or
all of the operations of the electronic device 1300. The processing
device(s) 1302 can communicate, either directly or indirectly, with
substantially all of the components of the device. For example, one
or more system buses 1316 or other communication mechanisms can
provide communication between the processing device(s) 1302, the
memory 1304, the I/O device(s) 1306, the power source 1308, the one
or more sensors 1310, the network communication interface 1312,
and/or the display 1314. At least one processing device can be
configured to determine an amount of force and/or a change in force
applied to an I/O device 1306, the display, and/or the electronic
device 1300 based on a signal received from one or more transistor
strain sensors.
[0080] The processing device(s) 1302 can be implemented as any
electronic device capable of processing, receiving, or transmitting
data or instructions. For example, the one or more processing
devices 1302 can be a microprocessor, a central processing unit
(CPU), an application-specific integrated circuit (ASIC), a digital
signal processor (DSP), or combinations of multiple such devices.
As described herein, the term "processing device" is meant to
encompass a single processor or processing unit, multiple
processors, multiple processing units, or other suitably configured
computing element or elements.
[0081] The memory 1304 can store electronic data that can be used
by the electronic device 1300. For example, the memory 1304 can
store electrical data or content such as audio files, document
files, timing and control signals, operational settings and data,
and image data. The memory 1304 can be configured as any type of
memory. By way of example only, memory 1304 can be implemented as
random access memory, read-only memory, Flash memory, removable
memory, or other types of storage elements, in any combination.
[0082] The one or more I/O devices 1306 can transmit and/or receive
data to and from a user or another electronic device. Example I/O
device(s) 1306 include, but are not limited to, a touchscreen or
track pad, one or more buttons, a microphone, a haptic device, a
speaker, and/or a force sensor 1318. The force sensor 1318 can
include one or more force sensitive structures. The force sensitive
structure(s) can be configured as one of the force sensitive
structures discussed earlier in conjunction with FIGS. 3-13.
[0083] As one example, the I/O device 106 shown in FIG. 1 may
include a force sensor 1318. As described earlier, the force sensor
1318 can include one or more force sensitive structures that are
configured according to one of the embodiments shown in FIGS. 3-12.
An amount of force that is applied to the I/O device 106, and/or a
change in an amount of applied force can be determined based on the
signal(s) received from the force sensitive structure(s).
[0084] The power source 1308 can be implemented with any device
capable of providing energy to the electronic device 1300. For
example, the power source 1308 can be one or more batteries or
rechargeable batteries, or a connection cable that connects the
electronic device to another power source such as a wall
outlet.
[0085] The electronic device 1300 may also include one or more
sensors 1310 positioned substantially anywhere on or in the
electronic device 1300. The sensor or sensors 1310 may be
configured to sense substantially any type of characteristic, such
as but not limited to, images, pressure, light, heat, force, touch,
temperature, humidity, movement, relative motion, biometric data,
and so on. For example, the sensor(s) 1310 may be an image sensor,
a temperature sensor, a light or optical sensor, an accelerometer,
an environmental sensor, a gyroscope, a magnet, a health monitoring
sensor, and so on.
[0086] As one example, the electronic device shown in FIG. 1 may
include a force sensor 1320 in or under at least a portion of the
enclosure 102. The force sensor 1320 can include one or more force
sensitive structures that may be configured as one of the force
sensitive structures discussed earlier in conjunction with FIGS.
3-12. An amount of force that is applied to the enclosure 102,
and/or a change in an amount of applied force can be determined
based on the signal(s) received from the strain sensor(s).
[0087] The network communication interface 1312 can facilitate
transmission of data to or from other electronic devices. For
example, a network communication interface can transmit electronic
signals via a wireless and/or wired network connection. Examples of
wireless and wired network connections include, but are not limited
to, cellular, Wi-Fi, Bluetooth, infrared, RFID, Ethernet, and
NFC.
[0088] The display 1314 can provide a visual output to the user.
The display 1314 can be implemented with any suitable technology,
including, but not limited to, a multi-touch sensing touchscreen
that uses liquid crystal display (LCD) technology, light emitting
diode (LED) technology, organic light-emitting display (OLED)
technology, organic electroluminescence (OEL) technology, or
another type of display technology. In some embodiments, the
display 1314 can function as an input device that allows the user
to interact with the electronic device 1300. For example, the
display can include a touch sensor 1322. The touch sensor 1322 can
allow the display to function as a touch or multi-touch
display.
[0089] Additionally or alternatively, the display 1314 may include
a force sensor 1324. In some embodiments, the force sensor 1324 is
included in a display stack of the display 1314. The force sensor
1324 can include one or more force sensitive structures. An amount
of force that is applied to the display 1314, or to a cover layer
disposed over the display, and/or a change in an amount of applied
force can be determined based on the signal(s) received from the
force sensitive structure(s). The force sensitive structure(s) can
be configured as one of the force sensitive structures discussed
earlier in conjunction with FIGS. 2-12.
[0090] It should be noted that FIG. 13 is exemplary only. In other
examples, the electronic device may include fewer or more
components than those shown in FIG. 13. Additionally or
alternatively, the electronic device can be included in a system
and one or more components shown in FIG. 13 is separate from the
electronic device but in communication with the electronic device.
For example, an electronic device may be operatively connected to,
or in communication with a separate display. As another example,
one or more applications or data can be stored in a memory separate
from the electronic device. In some embodiments, the separate
memory can be in a cloud-based system or in an associated
electronic device.
[0091] Various embodiments have been described in detail with
particular reference to certain features thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the disclosure. For example, the one or
more strain sensors can be formed with an opaque material.
Additionally or alternatively, the one or more strain sensors can
be formed on one layer and the strain signal line(s) on another
layer such that a strain sensor and corresponding strain signal
line(s) are not co-planar (on different planar surfaces). A via can
be formed through the interposing layer or layers to produce an
electrical contact between the strain sensor and the strain signal
lines.
* * * * *