U.S. patent application number 15/268418 was filed with the patent office on 2017-01-05 for touch and hover sensing.
The applicant listed for this patent is Apple Inc.. Invention is credited to David T. AMM, Jeffrey Traer BERNSTEIN, Reese T. CUTLER, Brian Michael KING, Brian Richards LAND, Omar S. LEUNG, Christopher Tenzin MULLENS.
Application Number | 20170003816 15/268418 |
Document ID | / |
Family ID | 43427088 |
Filed Date | 2017-01-05 |
United States Patent
Application |
20170003816 |
Kind Code |
A1 |
BERNSTEIN; Jeffrey Traer ;
et al. |
January 5, 2017 |
TOUCH AND HOVER SENSING
Abstract
A capacitive sensing apparatus is disclosed. In some examples,
the capacitive sensing apparatus includes a sensor control system
configured to: during a first scan of the sensor array: transmit a
first alternating current (AC) signal concurrently with a second
alternating current (AC) signal to the sensor array, transmit the
first AC signal to the first electrode of the sensor array, measure
a self capacitance at the first input location, and transmit the
second AC signal to the second electrode of the sensor array
without measuring a self capacitance at the second input location,
and during a second scan of the sensor array: transmit the first AC
signal concurrently with the second AC signal to the sensor array,
transmit the first AC signal to the first electrode of the sensor
array without measuring the self capacitance at the first input
location, and measure the self capacitance at the second input
location.
Inventors: |
BERNSTEIN; Jeffrey Traer;
(San Francisco, CA) ; AMM; David T.; (Tucson,
AZ) ; LEUNG; Omar S.; (Palo Alto, CA) ;
MULLENS; Christopher Tenzin; (San Francisco, CA) ;
KING; Brian Michael; (Saratoga, CA) ; LAND; Brian
Richards; (Woodside, CA) ; CUTLER; Reese T.;
(Mountain View, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
|
|
Family ID: |
43427088 |
Appl. No.: |
15/268418 |
Filed: |
September 16, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15083102 |
Mar 28, 2016 |
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15268418 |
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|
12501382 |
Jul 10, 2009 |
9323398 |
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15083102 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 2203/04107
20130101; G06F 3/041662 20190501; G06F 3/0416 20130101; G06F 3/044
20130101; G06F 3/0446 20190501; G06F 2203/04101 20130101; G06F
3/04845 20130101; G06F 3/04817 20130101; G06F 3/0486 20130101 |
International
Class: |
G06F 3/041 20060101
G06F003/041; G06F 3/044 20060101 G06F003/044 |
Claims
1. A capacitive sensing apparatus comprising: a sensor array
comprising: a first electrode at a first input location; and a
second electrode at a second input location adjacent to the first
input location; and a sensor control system configured to: during a
first scan of the sensor array: transmit the first AC signal to the
first electrode of the sensor array; measure a self capacitance at
the first input location; and transmit the second AC signal to the
second electrode of the sensor array without measuring a self
capacitance at the second input location; and during a second scan
of the sensor array: transmit the first AC signal to the first
electrode of the sensor array without measuring the self
capacitance at the first input location; and measure the self
capacitance at the second input location.
2. The capacitive sensing apparatus of claim 1, wherein the sensor
control system is further configured to: during a third scan of the
sensor array: transmit the first alternating current (AC) signal
concurrently with the second alternating current (AC) signal to the
sensor array; transmit the first AC signal to the first electrode
of the sensor array; measure the self capacitance at the first
input location; transmit the second AC signal to the second
electrode of the sensor array; and measure the self capacitance at
the first input location.
3. The capacitive sensing apparatus of claim 1, wherein the first
and second signals have a same voltage.
4. The capacitive sensing apparatus of claim 1, further comprising
an AC shield electrode, different from the first electrode and the
second electrode.
5. The capacitive sensing apparatus of claim 4, wherein the AC
shield is electrically isolated from the sensor array.
6. The capacitive sensing apparatus of claim 1, wherein the first
AC signal and the second AC signal are transmitted
concurrently.
7. The capacitive sensing apparatus of claim 1, wherein the sensor
control system is further configured to: during a mutual
capacitance scan of the sensor array: transmit the first AC signal
to the first electrode of the sensor array; measure a mutual
capacitance at the first input location; transmit the second AC to
the second electrode of the sensor array; and measure the mutual
capacitance at the second input location.
8. The capacitive sensing apparatus of claim 1, wherein the first
AC signal has a waveform and the second AC signal is generated from
a buffered copy of the waveform.
9. A method comprising: during a first scan of a sensor array:
transmitting a first alternating current (AC) signal concurrently
with a second alternating current (AC) signal to the sensor array;
transmitting the first AC signal to a first electrode of the sensor
array at a first input location; measuring a self capacitance at
the first input location; and transmitting the second AC signal to
a second electrode of the sensor array at a second input location
without measuring a self capacitance at the second input location,
the second input location different from the first input location;
and during a second scan of the sensor array: transmitting the
first AC signal concurrently with the second AC signal to the
sensor array; transmitting the first AC signal to the first
electrode of the sensor array without measuring the self
capacitance at the first input location; and measuring the self
capacitance at the second input location.
10. The method of claim 9, further comprising: during a third scan
of the sensor array: transmitting a first alternating current (AC)
signal concurrently with a second alternating current (AC) signal
to the sensor array; transmitting the first AC signal to the first
electrode of the sensor array; measuring the self capacitance at
the first input location; transmitting the second AC signal to the
second electrode of the sensor array; and measuring the self
capacitance at the first input location.
11. The method of claim 9, wherein the first and second signals
have a same voltage.
12. The method of claim 9, wherein the sensor array comprises an AC
shield electrode, different from the first electrode and the second
electrode.
13. The method of claim 12, wherein the AC shield is electrically
isolated from the sensor array.
14. The method of claim 12, wherein the first AC signal and the
second AC signal are transmitted concurrently.
15. The method of claim 9, further comprising: during a mutual
capacitance scan of the sensor array: transmitting the first AC
signal to the first electrode of the sensor array; measuring a
mutual capacitance at the first input location; transmitting the
second AC to the second electrode of the sensor array; and
measuring the mutual capacitance at the second input location.
16. The method of claim 9, wherein the first AC signal has a
waveform and the second AC signal is generated from a buffered copy
of the waveform.
17. A non-transitory computer-readable storage medium having stored
therein instructions, which when executed by a processor cause the
processor to perform a method comprising: during a first scan of a
sensor array: transmitting a first alternating current (AC) signal
concurrently with a second alternating current (AC) signal to the
sensor array; transmitting the first AC signal to a first electrode
of the sensor array at a first input location; measuring a self
capacitance at the first input location; and transmitting the
second AC signal to a second electrode of the sensor array at a
second input location without measuring a self capacitance at the
second input location, the second input location different from the
first input location; and during a second scan of the sensor array:
transmitting the first AC signal concurrently with the second AC
signal to the sensor array; transmitting the first AC signal to the
first electrode of the sensor array without measuring the self
capacitance at the first input location; and measuring the self
capacitance at the second input location.
18. The non-transitory computer readable medium of claim 17, the
method further comprising: during a third scan of the sensor array:
transmitting a first alternating current (AC) signal concurrently
with a second alternating current (AC) signal to the sensor array;
transmitting the first AC signal to the first electrode of the
sensor array; measuring the self capacitance at the first input
location; transmitting the second AC signal to the second electrode
of the sensor array; and measuring the self capacitance at the
first input location.
19. The non-transitory computer readable medium of claim 17,
wherein the sensor array comprises an AC shield electrode,
different from the first electrode and the second electrode.
20. The non-transitory computer readable medium of claim 17,
wherein the first AC signal has a waveform and the second AC signal
is generated from a buffered copy of the waveform.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/083,102, filed Mar. 28, 2016 and published
on Jul. 21, 2016 as U.S. Patent Publication No. 2016/0209982, which
is a continuation of U.S. patent application Ser. No. 12/501,382,
filed Jul. 10, 2009 and issued on Apr. 26, 2016 as U.S. Pat. No.
9,323,398, the contents of which are incorporated herein by
reference in their entirety for all purposes.
FIELD
[0002] This relates generally to touch and hover sensing, and in
particular, to improved capacitive touch and hover sensing.
BACKGROUND
[0003] Many types of input devices are presently available for
performing operations in a computing system, such as buttons or
keys, mice, trackballs, joysticks, touch sensor panels, 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 transparent touch sensor panel positioned in front of a
display device such as a liquid crystal display (LCD), or an
integrated touch screen in which touch sensing circuitry is
partially or fully integrated into a display, etc. Touch screens
can allow a user to perform various functions by touching the touch
screen using a finger, stylus or other object at a location that
may be dictated by a user interface (UI) being displayed by the
display device. In general, touch screens can recognize a touch
event and the position of the touch event on the touch sensor
panel, and the computing system can then interpret the touch event
in accordance with the display appearing at the time of the touch
event, and thereafter can perform one or more actions based on the
touch event.
[0004] Mutual capacitance touch sensor panels can be formed from a
matrix of drive and sense lines of a substantially transparent
conductive material such as Indium Tin Oxide (no), often arranged
in rows and columns in horizontal and vertical directions on a
substantially transparent substrate. Drive signals can be
transmitted through the drive lines, which can make it possible to
measure the static mutual capacitance at the crossover points or
adjacent areas (sensing pixels) of the drive lines and the sense
lines. The static mutual capacitance, and any changes to the static
mutual capacitance due to a touch event, can be determined from
sense signals that can be generated in the sense lines due to the
drive signals.
[0005] While some touch sensors can also detect a hover event,
i.e., an object near but not touching the touch sensor, typical
hover detection information may be of limited practical use due to,
for example, limited hover detection range, inefficient gathering
of hover information, etc.
SUMMARY
[0006] This relates to improved capacitive touch and hover sensing.
A capacitive sensor array can be driven with electrical signals,
such as alternating current (AC) signals, to generate electric
fields that extend outward from the sensor array through a touch
surface to detect a touch on the touch surface or an object
hovering over the touch surface of a touch screen device, for
example. The electric field can also extend behind the sensor array
in the opposite direction from the touch surface, which is
typically an internal space of the touch screen device. An AC
ground shield may be used to enhance the hover sensing capability
of the sensor array. The AC ground shield can be positioned behind
the sensor array and can be stimulated with signals having the same
waveform as the signals driving the sensor array. As a result, the
electric field extending outward from the sensor array can be
concentrated. In this way, for example, the hover sensing
capability of the sensor array may be improved.
[0007] Hover sensing may also be improved using methods to detect a
hover position of an object outside of a space directly above the
touch surface. In particular, the hover position and/or height of
an object that is nearby, but not directly above, the touch surface
(in other words, an object outside of the space directly above the
touch surface), e.g., in the border area at the end of a touch
screen, may be determined using measurements of sensors near the
end of the touch screen by fitting the measurements to a model.
Other improvements relate to the joint operation of touch and hover
sensing, such as determining when and how to perform touch sensing,
hover sensing, both touch and hover sensing, or neither.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present disclosure, in accordance with one or more
various embodiments, is described in detail with reference to the
following figures. The drawings are provided for purposes of
illustration only and merely depict example embodiments of the
disclosure. These drawings are provided to facilitate the reader's
understanding of the disclosure and should not be considered
limiting of the breadth, scope, or applicability of the disclosure.
It should be noted that for clarity and ease of illustration these
drawings are not necessarily made to scale.
[0009] FIGS. 1A-1B illustrate an example sensor array and AC ground
shield according to embodiments of the disclosure.
[0010] FIGS. 2A-2B illustrate example sensor array configurations
with and without an AC ground shield according to embodiments of
the disclosure.
[0011] FIG. 3 illustrates an example touch screen according to
embodiments of the disclosure.
[0012] FIG. 4 illustrates an object directly above an example touch
screen according to embodiments of the disclosure.
[0013] FIG. 5 illustrates an object outside of a space directly
above an example touch screen according to embodiments of the
disclosure.
[0014] FIG. 6 illustrates example capacitance measurements
according to embodiments of the disclosure.
[0015] FIG. 7 is a flowchart of an example method of determining a
hover position/height according to embodiments of the
disclosure.
[0016] FIG. 8 illustrates an example touch and hover sensing system
according to embodiments of the disclosure.
[0017] FIG. 9 illustrates an example touch and hover sensing system
according to embodiments of the disclosure.
[0018] FIG. 10 is a flowchart of an example method of detecting
touch and hover events according to embodiments of the
disclosure.
[0019] FIG. 11 is a flowchart of an example method of operating a
touch and hover sensing system according to embodiments of the
disclosure.
[0020] FIG. 12A illustrates an example mobile telephone that can
include improved capacitive touch and hover sensing according to
embodiments of the disclosure.
[0021] FIG. 12B illustrates an example digital media player that
can include improved capacitive touch and hover sensing according
to embodiments of the disclosure.
[0022] FIG. 12C illustrates an example personal computer that can
include improved capacitive touch and hover sensing according to
embodiments of the disclosure.
DETAILED DESCRIPTION
[0023] In the following description of 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 that
can be practiced. It is to be understood that other embodiments can
be used and structural changes can be made without departing from
the scope of the disclosed embodiments.
[0024] This relates generally to touch and hover sensing, and more
particularly, to improved capacitive touch and hover sensing. For
example, an alternating current (AC) ground shield may be used to
enhance the hover sensing capability of a sensor array, such as a
capacitive touch sensor array. Electrical signals, such as AC
signals, transmitted to a capacitive touch sensor array in a touch
screen can generate electric fields that extend outward from the
sensor array through a touch surface to detect a touch on the touch
surface or an object hovering over the touch surface. The electric
field can also extend behind the sensor array in the opposite
direction from the touch surface, which is typically an internal
space of the touch screen device. An AC ground shield can be
positioned behind the sensor array, and the AC ground shield can be
stimulated with signals having the same waveform as the AC signals,
for example. As a result, the electric field extending outward from
the sensor array can be concentrated, as described in more detail
below. In this way, for example, the hover sensing capability of
the sensor array may be improved.
[0025] Hover sensing may also be improved using methods to detect a
hover position of an object outside of a space directly above the
touch surface. In particular, the hover position and/or height of
an object that is nearby, but not directly above, the touch surface
(in other words, an object outside of the space directly above the
touch surface), e.g., in the border area at the end of a touch
screen, may be determined using measurements of sensors near the
end of the touch screen by fitting the measurements to a model, as
described in more detail below. Other improvements relate to the
joint operation of touch and hover sensing, such as determining
when and how to perform touch sensing, hover sensing, both touch
and hover sensing, or neither, as described in more detail
below.
[0026] FIGS. 1A and 1B show an example embodiment of a capacitive
touch and hover sensing apparatus that includes an AC ground shield
(also referred to as a "driven shield").
[0027] FIG. 1A shows a portion of a touch and hover sensing
apparatus 100 with a sensor array 101 that includes an array of
horizontal lines 103 and vertical lines 105. Horizontal lines 103
and vertical lines 105 can be, for example, electrically conductive
lines in a self capacitive sensing system. In other embodiments,
other types of sensing schemes may be used, such as mutual
capacitive, optical, ultrasonic, etc. In some embodiments, such as
touch screens, for example, lines 103 and/or 105 can be formed of
substantially transparent conductive materials. In some
embodiments, such as trackpads, for example, lines 103 and/or 105
may be formed of a non-transparent conductive material.
[0028] Touch and hover sensing apparatus 100 also includes a touch
and hover control system 107 that can drive sensor array 101 with
electrical signals, e.g., AC signals, applied to horizontal lines
103 and/or vertical lines 105. The AC signals transmitted to sensor
array 101 create electric fields extending from the sensor array,
which can be used to detect objects near the sensor array. For
example, an object placed in the electric field near sensor array
101 can cause a change in the self capacitance of the sensor array,
which can be measured by various techniques. Touch and hover
control system 107 can measure the self capacitance of each of the
horizontal and vertical lines to detect touch events and hover
events on or near sensor array 101.
[0029] The maximum range of detection can depend on a variety of
factors, including the strength of the electric field generated by
sensor array 101, which can depend on the voltage, i.e., amplitude,
of the AC signals used for detection. However, the AC signal
voltage may be limited by a variety of design factors, such as
power limitations, impedance limitations, etc. In some
applications, such as consumer electronics in general and portable
electronics in particular, the limited maximum voltage of the AC
signals may make it more difficult to design touch and hover
sensing systems with acceptable detection ranges.
[0030] In this regard, FIG. 1B shows an AC ground shield system
that can be used with sensor array 101. The AC ground shield system
includes an AC ground shield 201 and an AC shield driving system
203. AC ground shield 201 can be positioned substantially behind
sensor array 101, that is, on the side of sensor array 101 opposite
to the touch and hover detection side of the sensor array. AC
shield driving system 203 can transmit AC signals to AC ground
shield 201 to create an electric field that can help concentrate
the electric field generated by sensor array 101 in a detection
space above sensor array 101 (shown as the z-direction in FIG.
1B).
[0031] FIGS. 2A and 2B illustrate an example of how the electric
field generated by sensor array 101 may be concentrated by AC
ground shield 201. FIG. 2A shows a stimulated horizontal conductive
line 103 of sensor array 101 in a configuration without AC ground
shield 201. An electric field 250 extends substantially radially
from horizontal conductive line 103 in all directions. FIG. 2B
illustrates how including AC ground shield 201 with the
configuration of FIG. 2A can concentrate electric field of
conductive line 103 into a different electric field 253. In FIG.
2B, horizontal conductive line 103 of sensor array 101 is
stimulated in the same way as in FIG. 2A, and AC ground shield 201
is stimulated in a substantially similar way as conductive line
103. For example, the AC signals transmitted to AC ground shield
201 can have substantially the same waveform as the AC signals
transmitted to sensor array 101, such that the voltage of the AC
ground shield can be substantially the same as the voltage of
sensor array 101 at any particular time. The stimulation of AC
ground shield generates an electric field 255. FIG. 2B shows
electric field 253 concentrated above (in the z-direction)
horizontal conductive line 103 due to the operation of AC ground
shield 201. In this way, for example, the addition of AC ground
shield 201 can help boost the detection range of sensor array
101.
[0032] In addition, AC ground shield 201 can reduce or eliminate
the electric field between sensor array 101 and AC ground shield
201. More particularly, even though the voltages on sensor array
101 and AC ground shield 201 may be changing over time, the change
can be substantially in unison so that the voltage difference,
i.e., electric potential, between the sensor array and the AC
ground shield can remain zero or substantially zero. Therefore,
little or no electric fields may be created between sensor array
101 and AC ground shield 201. FIG. 2B, for example, shows that the
space between horizontal conductive line 103 and AC ground shield
201 is substantially free of electric fields in the example
configuration.
[0033] FIG. 3 illustrates an example embodiment in which sensor
array 101, touch and hover control system 107, AC ground shield
201, and AC shield driving system 203 are implemented in a touch
screen 300. In this example, horizontal lines 103 and vertical
lines 105 can be electrodes formed of a substantially transparent
conductor. FIG. 3 shows a portion of touch screen 300 in which
sensor array 101 and AC ground shield 201 can be substantially
co-located with display circuitry 317, and in particular, AC ground
shield can be positioned substantially between display circuitry
317 and sensor array 101. A border 301 holds distal ends 303 of
sensor array 101. The user can view a displayed image through a
cover surface 305 and can, for example, touch the cover surface
with their fingers and/or hover their fingers near the cover
surface in a space 307 directly above sensor array 101 in order to
activate corresponding elements of a graphical user interface (GUI)
corresponding to the detected touch events and/or hover events. In
this example, touch and hover control system 107 transmits AC
signals having a waveform 311 on a transmission line 309 that
connects the touch and hover control system to sensor array 101.
Touch and hover control system 107 also transmits waveform 311 to a
memory 313 for storage. Memory 313 stores a buffered copy 315 of
waveform 311. AC shield driving system 203 reads buffered copy 315
of the waveform from memory 313 and generates corresponding AC
signals with waveform 311, which are then transmitted to AC ground
shield 201. In this example configuration, sensor array 101 can be
positioned substantially between AC ground shield 201 and cover
surface 305, and AC ground shield 201 operates as described above
to concentrate electric fields in detecting space 307 over cover
surface 305.
[0034] The configuration of AC ground shield 201 may also help to
shield sensor array 101 from other electronics and/or sources of
ground, such as from display circuitry 317 which can be driven by a
display driver 319 to generate an image viewed through cover
surface 305. In particular, as described above, AC ground shield
201 can help prevent or reduce an electric field emanating from
sensor array 101 in the direction of the AC ground shield. In the
configuration shown in FIG. 3, AC ground shield 201 can be
positioned between sensor array 101 and other internal electronics,
such as display circuitry 317 and display driver 319. Therefore, AC
ground shield 201 can prevent or reduce an electric field emanating
from sensor array 101 that could reach display circuitry 317 and
display driver 319. In this way, AC ground shield 201 may help
electrically isolate sensor array 101 from other internal
electronics in this example configuration, which may reduce
undesirable effects such as noise, stray capacitance, etc. that
could interfere with the accurate measuring of capacitance changes
caused by objects touching/hovering in detection space 307.
[0035] Another type of AC shield, a transmission line AC shield
308, is shown in FIG. 3. Transmission line AC shield 308
substantially surrounds a portion of transmission line 309. AC
shield driving system 203 also uses buffered copy 315 to transmit
signals with waveform 311 to transmission line AC shield 308. This
can help to shield transmission line 309 by reducing electric
fields emanating from the transmission line. However, in contrast
to AC ground shield 201, transmission line AC shield 308 does not
serve to concentrate fields emanating from transmission line 309 to
boost a range of detection, for example.
[0036] FIG. 4 shows a finger 401 hovering in space 307 directly
above sensor array 101. Finger 401 can disturb electric field lines
403 from sensor array 101.
[0037] FIG. 5 shows finger 401 near distal end 303 and outside of
space 307. Even though finger 401 is outside of space 307 directly
above sensor array 101, the finger still disturbs some of the field
lines 501 emanating from some of the sensors of sensor array
101.
[0038] FIG. 6 illustrates capacitance measurements 601 representing
measurements from FIG. 4 and measurements 603 representing
measurements from the configuration in FIG. 5. Measurements 601 can
represent a typical shape of a set of capacitance measurements of
sensors of sensor array 101 near a touch object such as finger 401
shown in FIG. 4. In particular, measurements closer to the center
of finger 401 can be greater than measurements further from the
center. Therefore, the shape of measurements 601 can be modeled,
for some objects and sensor arrays, with a curve 605, such as a
Gaussian curve, for example. Curve 605 can have a local maximum
607, which can represent the center of finger 401, for example.
Curve 605 also has tail ends on either side of local maximum 607.
FIG. 6 also shows measurements 603, which represent the set of
capacitance measurements measured by sensors near distal end 303 of
sensor array 101 after finger 401 has traveled outside of space
307, past distal end 303. In this case, measurements 603 represent
only a tail end 609 of the curve that would be measured if finger
401 were inside of space 307. In other words, measurements 603 are
an incomplete set of measurements, at least as compared to
measurements 601.
[0039] In typical algorithms used to determine position and/or
hover height of an object directly above a sensor array of a touch
screen, for example, a full set of measurements such as
measurements 601 can provide enough data to determine the position
from a determination of local maximum 607. In this case, the
determination of local maximum 607 can be easily made because the
set of measurements 601 spans local maximum 607. In other words,
local maximum 607 can be within the range of measurements 601. On
the other hand, measurements 603 represent only tail end 609
portion of a complete curve, which does not include direct
information of a local maximum. Thus, while the shape of tail end
609 can be known, the shape of the complete curve that would be
measured if sensor array 101 extended beyond distal end 303 can be
unknown.
[0040] FIG. 6 shows one possible estimate of an unknown curve 611
based on a set of unknown measurements 615. Unknown curve 611 and
unknown measurements 615 are not actually measured, but are
provided for purposes of illustration to show the general idea of
how tail end measurements caused by an object near a distal end of
an array of sensors and outside of the space directly above the
array may be used to detect a hover position and/or hover height of
the object. In particular, it may be recognized that measurements
603 represent a tail end 609 of unknown curve 611 and at that
determining the parameters of unknown curve 611, and consequently
determining unknown local maximum 613, can provide information
about the hover position and/or height of the object. Consequently,
a hover position of the object outside of the range of sensor
positions of sensor array 101 may be determined based on the
determined local maximum 613.
[0041] FIG. 7 shows an example method of detecting a hover position
of an object outside of space 307 using measurements 603. The
example method of FIG. 7, and other methods described herein, may
be performed in, for example, touch and hover control system 107, a
general purpose processor such as a central processing unit (CPU)
(not shown), and/or another processor, and results may be stored
in, for example, memory 313 and/or another memory (not shown) as
one skilled in the art would readily understand in view of the
present disclosure. Referring to FIG. 7, measurements 603 can be
obtained (701) and fit (702) to a model including a local maximum
outside of space 307. A variety of models may be used, as well as a
variety of fitting methods, to fit measurements 603 to determine
the hover position of finger 401. For example, a Gaussian curve may
be used as a model of the type of curve to fit to measurements 603.
In particular, it may be observed from FIG. 6 that curve 605, which
approximates one set of measurements 601 of finger 401 in one
location, appears substantially Gaussian-shaped. Therefore, it may
be reasonable to assume that sensor readings made by an object
similar to finger 401 will be Gaussian-shaped. In this case, the
model selected to fit measurements 603 can be a Gaussian curve.
[0042] Various methods can be used to fit a Gaussian curve to
measurements 603. For example, one method that may be used is a
maximum likelihood estimate method. In this case, for example,
parameters of a Gaussian curve, such as maximum height and standard
deviation, may be adjusted until differences (errors) between the
estimated Gaussian curve and measurements 603 are minimized. The
Gaussian curve with the lowest estimated error can be used to
determine unknown local maximum 613, which can represent the
position of finger 401 outside of space 307.
[0043] In some embodiments, the model used may be another type of
curve, for example a modified Gaussian curve, a custom curve
determined from previous data, etc. In some embodiments, the model
used may not be a curve at all, but may simply be a set of
parameters stored in a lookup table (LUT). In this case, individual
sensor measurements may be individually fit to the values stored in
the lookup table, and once the best match is found, the lookup
table can simply return a single value representing the determined
hover position of the object. The hover position values in the
lookup table can be based on, for example, empirical data of hover
positions corresponding to particular sensor measurements,
previously calculated curve modeling, etc.
[0044] In some embodiments, other parameters may be used in the
determination of hover position and/or height. For example, if the
object's size, conductivity, etc., are known, these parameters may
be included when fitting the measured capacitances to the model. In
some embodiments, a model can be based on a previous set of
capacitance measurements of the object that includes a local
maximum.
[0045] In some embodiments, information regarding object size,
velocity, etc., may be taken into consideration in determining a
model to be used in fitting the capacitance measurements. For
example, FIGS. 4-6 illustrate an example situation in which a
finger 401 travels from the middle of sensor array 101 toward
distal end 303 and then past distal end 303 and outside of space
307. In this example case, the method could record the set of
measurements 601 as the model to which measurements 603 will be
fitted. The measurements 601 may be stored directly into a lookup
table, for example. In another embodiment, measurements 601 may be
interpolated to generate a model curve for use in fitting
measurements 603.
[0046] In some embodiments, other information about finger 401,
such as the finger's velocity, may be used when fitting
measurements 603. For example, the velocity of finger 401, which
may be determined by a separate algorithm, may be used as a
parameter in the model used during the fitting process. In this
way, a curve or representation of measurements 601 may be tracked
as finger 401 travels outside of space 307, such that information
regarding the local maximum of the curve can be maintained even
though the local maximum may not be directly detected in
measurements 603.
[0047] In some embodiments, multiple models may be considered
during fitting of the measurements. For example, the method may
determine that more than one object is causing the particular
capacitance measurements near a distal end of the sensor array, and
the method may use more than one model and/or fitting method to
attempt to fit the capacitance measurements to one or more objects
and/or types of objects. For example, the method may determine that
the capacitance measurements are caused by multiple objects of the
same type, such as "three fingers", or "two thumbs", etc. The
method may determine that the capacitance measurements are caused
by objects of different types, such as "a finger and a thumb", or
"a first and a thumb", etc. The method may determine that the
capacitance measurements are caused by a variety of numbers and
types of objects, such as "two fingers and a fist", or "a left
thumb, a right finger, and a palm", etc. The method may fit
different models, corresponding to the different number and/or type
of objects, to different portions of the capacitance measurements.
For example, the method may determine that the capacitance
measurements are caused by two objects, e.g., a finger that was
previously tracked as it moved off of the sensor array and an
unknown object estimated to be a thumb. In this case, the method
may attempt to fit the capacitance measurements corresponding to
the finger to previously stored data by fitting individual sensor
measurements to previously stored values in a LUT and fit the
capacitance measurements corresponding to the thumb to a Gaussian
curve using a maximum likelihood estimate of parameters associated
with a thumb. Thus, some embodiments may estimate the number of
objects and the parameters of each object when fitting the
capacitance measurements.
[0048] In some embodiments, the position and/or motion of an object
near the distal end of a sensor array and outside of the space
directly above the sensor array may be processed as a user input.
For example, a position and/or motion of an object may be processed
as an input to a graphical user interface (GUI) currently
displayed, as an input independent of a GUI, etc.
[0049] For example, the method described with reference to FIG. 7
may be used to determine a user input based on the position and/or
motion of one or more objects including objects near the distal end
of a sensor array and outside of the space directly above the
sensor array. The hover position of an object in a border area
outside the sensor array may be measured multiple times to
determine multiple hover positions. The motion of the object can be
determined corresponding to the multiple measured hover positions,
and an input can be detected based on the determined motion of the
object. For example, a finger detected moving upwards in a border
area may be interpreted as a user input to increase the volume of
music currently being played. In some embodiments, the user input
may control a GUI. For example, a finger detected moving in a
border area may control a GUI item, such as an icon, a slider, a
text box, a cursor, etc., in correspondence with the motion of the
finger.
[0050] In some embodiments, a user input can be based on a
combination of information including the position and/or motion of
an object directly above the sensor array and the position and/or
motion of an object near the distal end of the sensor array and
outside of the space directly above the sensor array. Referring to
FIGS. 3-5, for example, a GUI may be displayed at cover surface
305. The method described above with reference to FIG. 7 may be
used, for example, to control the motion of a GUI item as finger
401 travels off of the touch screen. For example, finger 401 may
initiate an input direct above sensor array 101 to "drag" an icon
displayed by the GUI. The icon may be controlled by display driver
319 to move along a path corresponding to the motion of finger 401
inside of space 307. If finger 401 is detected to move outside of
space 307 and to stop at a position near the distal end of sensor
array 101, display driver 319 can control the icon to continue
moving along the path of the finger just prior to the finger moving
off of the touch screen. Display driver 319 can cease the motion of
the icon when finger 401 is detected to move away from its stopped
position. This may be helpful to allow dragging and/or pointing
actions to be continued even when a finger, for example, moves off
of the touch screen.
[0051] FIGS. 8-11 describe examples of different hardware,
software, and firmware embodiments that can perform joint
operations of touch sensing and hover sensing. For example, in some
embodiments, one set of sensors can be used for hover sensing and
another set of sensors can be used for touch sensing. For instance,
electrodes configured for self-capacitance measurements can be used
for hover sensing, and electrodes configured for mutual capacitance
measurements can be used for touch sensing. In these cases,
switching between touch sensing and hover sensing may be done to
save power, reduce interference, etc. In other embodiments, the
same sensors may be shared between hover sensing and touch sensing.
In these cases, switching may be necessary in order to utilize
shared circuit elements, for example. Software and/or firmware may
control the joint operation of touch and hover sensing. For
example, depending on the particular configuration, software and/or
firmware may determine when to switch between touch sensing and
hover sensing, e.g., in single-mode operation, determine when to
perform touch and hover sensing concurrently, e.g., in multi-mode
operation, activate different portions of a sensor to perform touch
and/or hover sensing, etc.
[0052] FIGS. 8-9 illustrate example embodiments of hardware
switching that may be used to switch between touch sensing and
hover sensing.
[0053] FIG. 8 shows an example touch and hover sensing system 800
including a sensor array 801 that includes touch and hover
circuitry 803 and touch circuitry 805. For example, touch and hover
circuitry 803 can be a set of multiple conductive lines that can
operate as a self-capacitance sensor to sense hover events, and
touch circuitry 805 can be another set of multiple conductive lines
that can sense touch events when paired with the conductive lines
of touch and hover circuitry 803. Therefore, sensor array 801
includes common circuitry that operates in both the touch sensing
phase and the hover sensing phase. A sensor control system 807 can
operate sensor array 801 to detect both touch and hover, by
transmitting signals corresponding to hover sensing to touch and
hover circuitry 803 only, and by transmitting signals corresponding
to touch sensing to touch and hover circuitry 803 and touch
circuitry 805. Therefore sensor control system 807 can serve as an
integrated touch control system and hover control system, and
determine when to switch between touch sensing and hover sensing,
as described in more detail below.
[0054] FIG. 9 shows an example touch and hover sensing system 900
including a sensor array 901 and a sensor control system 903.
Sensor control system 903 includes a switching system 905, a touch
control system 907, a hover control system 909, and a low-leakage
analog switch 911. In operation, switching system 905 determines
when switching from touch sensing to hover sensing, and vice versa,
should occur and operates low-leakage analog switch 911 to switch
between touch control system 907 and hover control system 909
accordingly. During a touch sensing phase, touch control system
transmits an AC signal to sensor array 901 and measures a
capacitance of the sensor array resulting from the AC signal.
During a hover sensing phase, hover control system 909 transmits an
AC signal to sensor array 901 and measures a capacitance of sensor
array 901 resulting from the AC signal.
[0055] FIGS. 10-11 show example methods of joint touch and hover
sensing, which can be implemented, for example, in software,
firmware, application-specific integrated circuits (ASICs),
etc.
[0056] FIG. 10 shows an example method for detecting a touch event
and a hover event on or near a touch and hover sensing apparatus,
such as touch screen 300. In a touch detection phase, touch and
hover control system 107 can transmit (1001) a first AC signal to
sensor array 101, and can measure (1002) a first capacitance of the
sensor array. Touch and hover control system 107 can detect (1003)
a touch event based on the first capacitance, and store (1004)
touch event data, e.g., position, size, shape, gesture data, etc.,
in a memory. In a hover detection phase, touch and hover control
system 107 can transmit (1005) a second AC signal to sensor array
101, and can measure (1006) a second capacitance of the sensor
array. Touch and hover control system 107 can detect (1009) a hover
event based on the second capacitance, and store (1010) hover event
data, such as position, height, size, gesture data, etc.
[0057] Other operations can be occurring during or in between the
touch detection and hover detection phases. For example, display
driver 319 may transmit image signals to display circuitry 317 in a
display phase that can be in between the touch sensing phase and
the hover sensing phase. During the touch and/or hover sensing
phases, AC shield driving system 203 may operate as described above
to shield transmission line 309 using transmission line AC shield
308, and to boost the electric field emanating from cover surface
305 using AC shield 201. The touch detection phase and hover
detection phase may occur in any order.
[0058] Some embodiments may not be able to sense touch and hover
concurrently, i.e., only a single mode of sensing (non-overlapping
touch/hover sensing) is possible. In this case, in some embodiments
touch sensing and hover sensing may be time multiplexed, that is,
touch and hover sensing can be performed during different,
non-overlapping periods of time. Various methods can be implemented
for deciding how to time multiplex the sensing operations, i.e.,
deciding whether touch sensing or hover sensing (or neither) should
be performed at a particular time.
[0059] In some embodiments, touch and hover sensing can operate
concurrently, i.e., multi-mode sensing. Even if a system can
perform multi-mode touch and hover sensing, it may be advantageous
to perform single mode sensing in some cases. For example, if
either touch sensing or hover sensing is not needed at a particular
time, switching to single mode sensing to save power may be
desirable.
[0060] In some embodiments, the operation of touch sensing and
hover sensing can be determined by a fixed schedule. In other
embodiments, the time and duration of touch and hover sensing can
be varied dynamically, for example, by setting the system to
operate in one of a number of operational modes including the touch
sensing mode and the hover sensing mode, and possibly other modes,
such as a display mode. For instance, FIG. 11 shows an example
method for determining whether to sense touch and/or hover. A touch
sensing operation can be performed (1101), and can determine (1102)
whether a touch is detected. If a touch is detected, the system can
perform (1103) both touch and hover sensing, either by switching
between the two, or by performing touch and hover sensing
concurrently if the system is capable of multi-mode sensing. Both
touch and hover sensing can be performed after a touch is detected
because the touch may indicate a period of user activity during
which a user may perform hover events and touch events.
[0061] If a touch is not detected at 1102, the system can perform
(1104) hover detection, and can determine (1105) whether a hover is
detected. If a hover is detected, the system can perform (1103)
both touch and hover sensing, because the hover may indicate a
period of user activity. If a hover is not detected at 1105, the
system can perform (1104) hover detection again. As long as a hover
is not detected, the system may not need to perform touch
detection, because any approaching object will cause a hover
detection before the object can touch down on the sensing
system.
[0062] Other factors may be used to determine whether to detect
touch, hover, both or neither. For example, some embodiments may
detect an approaching object during hover sensing and wait until
the object gets close to the touch surface to perform touch
sensing. In other words, a distance threshold can be used to
activate touch sensing. In some embodiments, the touch/hover mode
may be determined by a particular software application that may
require, for example, touch data but not hover data. In some
embodiments, the current number and/or position of touches may be
used as a factor. For example, a small mobile touch screen device
may alternate between touch sensing and hover sensing until a
predetermined number of contacts, e.g., five, touch the touch
surface. When five touch contacts are detected, the device can
cease detecting hover and can detect only touch because a user is
unlikely to use sixth object to perform a hover, for example.
[0063] Some embodiments may be capable of multi-mode operation,
i.e., performing touch sensing and hover sensing concurrently. For
example, some embodiments can use frequency multiplexing to combine
AC signals used for touch sensing with different frequency AC
signals used for hover sensing. In some embodiments, code division
multiplexing of the AC signals can be used to perform concurrent
touch sensing and hover sensing.
[0064] Frequency multiplexing and code division multiplexing can
allow circuit elements, such as sensing electrodes, to be used to
detect touch and hover concurrently. For example, an entire array
of sensors may be simultaneously stimulated to detect touch and
hover.
[0065] In some embodiments, touch sensing and hover sensing may be
space multiplexed by, e.g., operating one portion of a sensor array
for touch sensing and concurrently operating another portion of the
sensor array for hover sensing. For example, an AC signal used for
touch sensing can be transmitted to a first group of sensors of the
sensor array, and an AC signal used for hover sensing can be
transmitted to a second group of sensors of the array. The groups
of sensors may be changed dynamically, such that touch and hover
sensing can be performed by different portions of the sensor array
at different times. For example, touch sensing can be activated for
portions of the sensor array on which touches are detected, and the
remaining sensors may be operated to detect hover. The system can
track moving touch objects and adjust the group of sensors sensing
touch to follow the moving object.
[0066] FIG. 12A illustrates an example mobile telephone 1236 that
can include touch sensor panel 1224 and display device 1230, the
touch sensor panel including improved capacitive touch and hover
sensing according to one of the various embodiments described
herein.
[0067] FIG. 12B illustrates an example digital media player 1240
that can include touch sensor panel 1224 and display device 1230,
the touch sensor panel including improved capacitive touch and
hover sensing according to one of the various embodiments described
herein.
[0068] FIG. 12C illustrates an example personal computer 1244 that
can include touch sensor panel (trackpad) 1224 and display 1230,
the touch sensor panel and/or display of the personal computer (in
embodiments where the display is part of a touch screen) including
improved capacitive touch and hover sensing according to the
various embodiments described herein.
[0069] While various embodiments have been described above, it
should be understood that they have been presented by way of
example only, and not by way of limitation. Likewise, the various
diagrams may depict an example architectural or other configuration
for the disclosure, which is done to aid in understanding the
features and functionality that can be included in the disclosure.
The disclosure is not restricted to the illustrated example
architectures or configurations, but can be implemented using a
variety of alternative architectures and configurations.
Additionally, although the disclosure is described above in terms
of various example embodiments and implementations, it should be
understood that the various features and functionality described in
one or more of the individual embodiments are not limited in their
applicability to the particular embodiment with which they are
described. They instead can be applied alone or in some
combination, to one or more of the other embodiments of the
disclosure, whether or not such embodiments are described, and
whether or not such features are presented as being a part of a
described embodiment. Thus the breadth and scope of the present
disclosure should not be limited by any of the above-described
example embodiments.
* * * * *