U.S. patent application number 16/372134 was filed with the patent office on 2019-12-05 for apparatus and method for determining a stimulus, including a touch input and a stylus input.
The applicant listed for this patent is Alsentis, LLC. Invention is credited to Robert G. Bos, David W. Caldwell, Stefan G. Kurek, William D. Schaefer.
Application Number | 20190369771 16/372134 |
Document ID | / |
Family ID | 49484036 |
Filed Date | 2019-12-05 |
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United States Patent
Application |
20190369771 |
Kind Code |
A1 |
Caldwell; David W. ; et
al. |
December 5, 2019 |
APPARATUS AND METHOD FOR DETERMINING A STIMULUS, INCLUDING A TOUCH
INPUT AND A STYLUS INPUT
Abstract
A capacitive sensor associated with a substrate is presented.
The electrode includes a self-capacitance; and a processing unit
electrically coupled to the electrode and configured to register a
first touch signature during a first touch event in response to an
object approaching the electrode. The first touch signature
occurring over a total time domain (T) between a first time and a
second time, between a first substantially constant
self-capacitance and a second substantially constant
self-capacitance.
Inventors: |
Caldwell; David W.;
(Holland, MI) ; Schaefer; William D.; (Grand
Rapids, MI) ; Bos; Robert G.; (Grand Haven, MI)
; Kurek; Stefan G.; (Grand Rapids, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Alsentis, LLC |
Holland |
MI |
US |
|
|
Family ID: |
49484036 |
Appl. No.: |
16/372134 |
Filed: |
April 1, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14396794 |
Oct 24, 2014 |
10248264 |
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PCT/US2013/038323 |
Apr 26, 2013 |
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16372134 |
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61639373 |
Apr 27, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 2203/04103
20130101; G06F 2203/04101 20130101; G06F 3/0446 20190501; G06F
3/0418 20130101; G06F 3/044 20130101; G06F 3/0412 20130101; G06F
2203/04104 20130101 |
International
Class: |
G06F 3/044 20060101
G06F003/044; G06F 3/041 20060101 G06F003/041 |
Claims
1. A capacitive sensor comprising: an electrode including a
self-capacitance; a touch substrate adjacent the electrode; and a
processing unit electrically coupled to the electrode and
configured to register a first touch signature during a first touch
event in response to an object approaching the electrode, the first
touch signature occurring over a total time domain (T) between a
first time and a second time, between a first substantially
constant self-capacitance and a second substantially constant
self-capacitance; a filter disposed between the electrode and the
processing unit to affect a signal indicative of a touch signature
during the first touch event in response to an object approaching
the electrode, wherein the first touch signature includes a rate of
change (ds/dt) of the electrode self-capacitance during a total
time domain (T) in combination with at least one of the following
parameters of the first touch event; an interval change in
self-capacitance (ds) during the total time domain (T), wherein the
interval change in self-capacitance (ds) is less than a total
change in self-capacitance (S) for the first touch event. an
interval time domain (di) corresponding to the interval change in
self-capacitance (ds), wherein the interval time domain (dt) is
less than the total time domain (T) for the touch event.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an apparatus and method for
detecting a stimulus, and more particularly, an apparatus and
method for detecting a touch input and stylus input. This
application claims priority to U.S. application Ser. No. 14/396,794
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] There exist numerous Human Machine Interface (HMI) devices
designed to sense the presence of human touch today. In some cases
these HMI interfaces include a stylus that is used to provide input
from the human to the machine interface. A stylus may completely
replace the direct human interface or may supplement the human
interface, these HMI devices may use light, sound
mechanical-electro (switches) magnetic fields, electric fields,
electromagnetic fields, or a combination of these stimuli.
[0003] Three prior and current touch technologies that exist today
and that use elechic fields are commonly refened to as projected
capacitance, capacitive, and differential sensing. Projected
capacitance is commonly associated with transparent touch screens
that are used in conjunction with displays of the same approximate
size and arc assembled with such displays in a manner as to allow
the light from the display to pass through the sensing elements of
the projected capacitance touch screen sensing elements. Projected
capacitance is usually implemented with high resolution
capabilities where the selection of an area of touch can be much
smaller than the actual size of a finger. Projected capacitance is
widely used on personal electronic devices such as cell phones,
personal digital assistants (PDAs), smart phones, notebooks, laptop
computers, laptop monitors, and other user devices that have
displays. Capacitance sensing, as opposed to projected capacitance,
is usually applied in applications where singular inputs are
processed that generally respond to much lower resolution than
projected capacitance, such as buttons or low resolution sliders.
These lower resolution input sensing applications use electrode
structures that arc designed to respond to a finger sized input.
Nonetheless, capacitance sensing can be used in place of projected
capacitance, and in principle projected capacitance is a subset
implementation of capacitance in general. Differential sensing
technology uses electric fields, low impedance sensing techniques,
and unique sensing electrodes that in conjunction with specific
electronic sensing circuits allow for the accurate, robust sensing
of human touch without the use of software.
[0004] Capacitance, projected capacitance, and differential sensing
have at least two common atldbutes: 1) they all use electric fields
as the stimulus for measuring the human machine interaction and 2)
they rely on a predetermined threshold that is determined by the
engineer which corresponds to a touch when a certain stimulus
change has occurred due to human machine interaction.
[0005] FIGS. 1 and 2 illustrate basic single input sensor
configurations for using multiple electrode and single electrode
capacitance sensing. FIG. 2 illustrates a simple capacitance sensor
with a single electrode 100 for sensing through a dielectric
substrate 102 The touch stimuli would be insetted on the opposite
side of the dielectric 102 of which the single electrode 100 is
located. FIG. 1 illustrates a multiple electrode capacitive sensor
having a dielectric substrate 102 and at least two electrodes 100,
104. Similarly to FIG. 2, the touch stimulus would be insetted on
the opposite side of the dielectric 102 of which the multiple
electrodes 100,104 are located. These capacitance sensing
techniques related to the structures in FIGS. 1 and 2 above sense
changes in capacitance from single or multiple electrodes in such a
manner that after the stimuli signal is processed there will be an
output signal that will change as a finger or stylus approaches the
sensing electrode(s). The output signal is processed in such a way
that when a certain value is reached (predetermined threshold) a
touch response will occur. This predetermined threshold would
conespond to a touch position located with a touch zone above the
touch surface. Changes--affected by manufacturing tolerances, the
dielectric constant, the dielectric thickness, the electrode area,
and the electronic sensing circuit variances--will cause the actual
touch location above the sensor electrode(s) to also vary.
[0006] Refer to FIGS. 3 through 7. FIG. 3 illustrates an electrical
schematic and block diagram of a single electrode capacitance
sensor as illustrated in FIG. 2 and timing diagrams illustrated in
FIGS. 4 through 7, a basic technique for detecting and processing a
touch input utilizing a single electrode. Ce represents the
effective net capacitance of a single electrode sensing element,
illustrated in FIG. 2. Ce will change depending on the capacitance
present, i.e. with "no touch" Ce will have lower value of
capacitance than when a "touch" is present in which case Ce will
have a higher value of capacitance Cs represents a sampling
capacitor for the Analog to Digital Converter 106. Pre-Determined
Threshold Circuitry 108, and Output Response 110. Control devices
A, B, and C represent electronic switches where when they arc
turned on will be in minimal resistance mode (ideally, zero ohms)
and when off are in high resistance mode (ideally, infinite
resistance).
[0007] FIGS. 4, 5, 6. and 7 are timing diagrams used to describe
the basic operation of a sensing technique for sensing a touch
input using a single electrode Ce. FIG. 4 illustrates the timing
diagram for a control signal for control device A. When the control
signal is at a value of 3.00 the control device is on and when the
control signal is at a value 0.00 the control device is off. The
same hold trues also for control signals for control devices B and
C in FIGS. 5 and 6. At time t1 in FIG. 6 control signal C goes high
causing control device to turn on connecting Ce to Cs. Also at time
t1 control signals A and B are low as indicated turning off control
devices A and B. At time t2 control device A is turned on
discharging any charge that is present on Ce and Cs ground as
indicated by the voltages Vs dropping to 0.00 from a voltage value
of 1.00 in FIG. 7. At time t3 control device A is turned off. At
time t4 control device C is turned off isolating Ce from Cs. At
time t5 control device B is turned on charging sampling capacitor
Cs to Vdd. FIG. 7 illustrates the voltage Vs charging from a value
of 0.00 to a Vdd value of 3.00. At time t7 control device C is
turned on connecting Cs to Ce causing the charge on Cs to
redistribute to both Cs and Ce and therefore the voltage Vs to drop
propmiional to the amount of capacitance on Ce. The capacitance of
Cs is constant. The lower voltage will drop according to the below
equation:
Vs=Vdd*(Cs/(Cs+Ce))
At time t7 the "no touch" value of 1.00 is illustrated in FIG. 7.
If there were a touch event, the capacitance Ce would beat higher
value than the "no touch" capacitance value. Based on the above
stated equation, Vs is shown as a lower value of 0.500 in FIG. 7.
At time t8 the control device C is turned off disconnecting the
sensor capacitor Ce from the sample capacitor Cs. The value of Vs
would remain at the sampled value that is proportional to the touch
condition, a higher value for "no touch" condition and a lower
value for the "touch" condition.
[0008] An alternative capacitance detecting technique utilizing
multiple electrodes is described here. Refer to FIGS. 1, 8 through
12. FIG. 8 illustrates an electrical schematic and block diagram of
a multiple electrode capacitance sensor as illustrated in FIG. 1,
and liming diagrams illustrated in FIGS. 9 through 12, a basic
technique for detecting and processing a touch input utilizing a
multiple electrodes. Ce represents an effective net capacitance for
a multiple (two) electrode sensing clement, illustrated in FIG. 1.
Ce will change depending on the capacitance present, i.e. with "no
touch" Ce will have higher value of capacitance and when "touch" is
present Ce will have a lower value of capacitance. Cs represents a
sampling capacitor for the Analog to Digital Convelter. Control
devices A and C represent electronic switches where when they are
turned on will be in minimal resistance mode (ideally, zero ohms)
and when off ate in high resistance mode (ideally, infinite
resistance). Control device B is represented as a MOSFet circuit
for generating a drive signal on the output of control device B.
FIGS. 9, 10, 11, and 12 are timing, diagrams used to describe the
basic operation of a sensing technique for sensing a touch input
using a multiple electrode capacitance sensor Ce. FIG. 11
illustrates the timing diagram for a control signal for control
device C. When the control signal is at a value of 3.00 the control
device is on and when the control signal is at a value 0.00 the
control device is off. The same hold trues also for the control
signal for control device A in FIG. 9. FIG. 10 illustrates the
liming diagram for the output ddve signal B which varies from a
value of 0.00 to a value of 3.00.
[0009] At time t1 in FIG. 11 control signal C goes high causing
control device C to turn on connecting Ce to Cs. Also at time t1
control signal A is low turning off control device A and output B
is low, both states shown in FIGS. 11 and 10 respectively. At time
t2 control device A is tinned on discharging any charge that might
be stored on Ce and Cs to ground as indicated by the voltage Vs
dropping to 0.00 from a voltage value of 1.00 in FIG. 12. At time
t3 control device A is turned off. At time t4 output device B is
turned on causing the voltage applied to sensor electrode structure
from a value of 0.00 to 3.00. The voltage stimulus will cause the
value of Vs to rise to a value that is proportional to the
capacitance of Ce as shown by the voltage rising from 0.00 at to a
value of 1.00 for a "no touch" condition. If there were a
finger/appendage or other touch input device to approach or come
into contact with the touch surface, then the capacitance of Ce
would be at a lower effective capacitance for a "touch condition"
causing the voltage to be at Vs to settle at a lower value as
indicated by the value of 0.500 at the "touch condition." Both of
these conditions are illustrated in FIG. 12. At time t5 control
device C is turned off isolating Ce from Cs. At time t6 output
device B goes low removing stimulus from the electrode structure
Ce. The capacitance of Cs is constant. The lower voltage will drop
according to the below equation:
Vs=Vdd*(Ce/(Cs+Ce)).
At time t6 the "no touch" value of 1.00 is illustrated in FIG. 12.
If there were a touch event, the capacitance Ce would be at higher
value than the "no touch" capacitance value Based on the above
stated equation, Vs is shown as a lower value of 0.500 in FIG. 12
capacitor Ce from the sample capacitor Cs. The value of Vs would
remain at the Vs value that is proportional to the touch condition,
a higher value for "no touch, condition and a lower value for the
"touch" condition. One useful attribute of this dual electrode
sensing technique is that if water were to lie on the touch surface
of the touch sensor structure, Ce would essentially go up in value,
then causing Vs to increase in value. This is useful in that the Vs
moves in the opposite direction for water as compared to a normal
touch event this information is very useful in inherently
discriminating against false touch events do to water laying on the
touch surface.
[0010] In both cases above, whether single electrode or dual
electrodes, the analog to digital converter 106 would convelt the
value of value of Vs to a digital value that can be processed by
the Predetermined Threshold Processing Circuit 108. Two examples of
how a Predetermined Threshold Value would be determined might be 1)
the Predetermined Threshold Value equals a Voltage value where when
Vs is equal to or less than that that same said Voltage value then
there is a valid touch event, i.e. valid touch event is present
when V(sample) Vp(predetermined threshold value), or 2) the
Predetermined Threshold Value equals a Voltage value where when
difference between the "no-touch" Vs value and the Vs is equal lo
or greater than that same said Voltage value then there is a valid
touch event, i.e. a valid touch event is present when [(the value
of a the "no touch" voltage)-(Vs)]>=V (predetermined threshold
value). Threshold Processing Circuitry 108 will take the digital
representation of the Vs and the Threshold Processing Circuitry 108
will then, using Predetermined Threshold Value processes similar to
that described above, process and decide if there is a valid touch
event to be processed by the Output Response circuit 110 for proper
interfacing to the outside world. The value for the Predetermined
Threshold Value must be determined by the designer of the
application of capacitance or field effect sensor. The
Predetermined Threshold Value is a value that ultimately is
compared to a sampled value that is proportional to the touch
stimulus that is then interpreted as a touch event. There are
numerous techniques that have been developed that would use tins
method of using a Predetermined Threshold Value. Even differential
sensing techniques using multiple sensing electrodes require that
the value sensed on one set of electrodes have some value relative
to oilier sets of electrodes, e.g. as an example in a differential
two electrode sensing structure both electrodes may need to be
equal to each other in order for there to be a touch event and one
of the electrodes may need to be less than the other for there to
not be a touch event (logically NOT touch). Regardless of the
technique, when using Predetermined Threshold techniques, there arc
other variables that can ultimately affect the value of sampled
voltages such as Vs in FIGS. 7 and 12, other than the "no touch" or
"touch" events. Changes in the dielectric constant of the touch
substrate, effective vaiiances in sensor pad area, variances in
area of finger coupling to the sensor structure, variances based on
tolerances of glass substrate, the variance in the sampling
circuitry, temperature, moisture, etc. can all lead to false or
under/over sensitive touch sensing response. FIGS. 1 and 2
illustrates the location above the touch surface dial corresponds
to the Predetermined Threshold Value such as to take into account
the variability of other factors that could influence the touch
sensitivity or "touch feel". If the designer had to account for the
use of gloves on a finger/appendage or other touch input device,
then the location above the touch surface that would correspond to
the Predetermined Threshold Value would have to be a greater
distance to accommodate the thickness of the glove insulation. Of
course when finger/appendage or other touch input device were to
approach the touch surface, the Predetermined Threshold Processing
Circuit 108 would register a valid touch event even though the
finger/appendage or other touch input device would not actually be
touching the touch surface. The conesponding location of the
Predetermined Threshold Value could be right at the touch surface.
In this case the designer would be taking into account the amount
of signal contribution due to the flattening of the
finger/appendage after initial contact to the touch surface. The
stimulus signal continues to increase as the capacitive coupling of
the finger to the glass increases which will causes the capacitance
Ce in FIG. 3 to increase and the capacitance Ce in FIG. 8 to
decrease. The designer has to lake into account all variables that
would affect what the Predetermined Threshold Value should belt
would be very important that after taking into account all of these
variables that the Predetermined Threshold Value is not set to such
a value such that when a finger/appendage or other touch input
device is brought to the touch surface there would not be a valid
touch event recognized. Conversely, the Predetermined Threshold
Value should not be set as to cause false actuations. All of the
variables above, including environmental conditions need to be
taken into account to determine the proper compromise for setting
the Predetermined Threshold Value.
SUMMARY OF THE INVENTION
[0011] A capacitive sensor is provided. In one embodiment, the
capacitive sensor includes first and second electrodes defining a
capacitive coupling and a processing unit electrically coupled to
the first and second electrodes to determine the presence of a
stimulus based on the rate of change of the capacitive coupling.
The processing unit is operative to determine the time rate of
change in response to the capacitive coupling being greater than a
predetermined threshold A substrate is positioned adjacent the
first and second electrodes, wherein the stimulus corresponds to
the placement of an object against the substrate.
[0012] In another embodiment, the capacitive sensor includes an
inner electrode and an outer electrode. The inner and outer
electrodes are substantially coplanar, and the outer electrode
substantially encompasses the inner electrode, being spaced apart
from the inner electrode. The inner electrode optionally defines
spaced apart segments, and the outer electrode is optionally
interposed between the spaced apart segments of the inner
electrode. The processing unit is operable to determine a rate of
change of the capacitive coupling between the inner and outer
electrodes in response to a stimulus, e.g., an object proximate the
capacitive sensor.
[0013] In still another embodiment, the capacitive sensor includes
a ligid substrate for supporting first and second coplanar
electrodes thereon, and includes a flexible substrate suppmicd
above the first and second electrodes by a plurality of spacers.
The flexible substrate is flexible downwardly toward the inner and
outer electrodes in response to a touch input on a portion of the
flexible substrate distal from the first and second electrodes. A
processing unit is operable to determine a rate of change of the
capacitive coupling between the first and second electrodes in
response to the touch input against the flexible substrate.
[0014] In yet another embodiment, the capacitive sensor includes a
strobe electrode spaced aprut from the first and second electrodes.
The strobe electrode is generally planru and is coextensive with
the first and second electrodes to define first and second
capacitive couplings, respectively. A rigid substrate is interposed
between the strobe electrode and the first and second electrodes.
The processing unit is operable to determine the rate of change of
the first and second capacitive couplings to indicate a touch
input, optionally in response to the first and second capacitive
couplings exceeding a predetennined threshold value.
[0015] In even another embodiment, the capacitive sensor include a
plurality of electrode rows extending in a first direction, and
includes a plurality of electrode columns extending in a second
direction transverse to the lust direction. The plurality of
electrode rows and the plurality of electrode columns are in
substantially non-overlapping alignment. In other embodiments, the
electrode columns are in overlapping alignment with the electrode
rows. The processing unit is operable to determine a rate of change
of the capacitance of the plurality of electrode rows and a rate of
change of the capacitance of the plurality of electrode columns to
indicate the presence of a stimulus in two dimensions. Adjacent
electrode rows optionally form a capacitive coupling, wherein the
processing unit is further adapted to measure a rate of change of
the capacitive coupling. In addition, adjacent electrode columns
optionally fonn a capacitive coupling, wherein the processing unit
is fmiher adapted to measure a rate of change of the capacitive
coupling.
[0016] These and other features and advantages of the present
invention will become apparent from the following description of
the invention, when viewed in accordance with the accompanying
drawings and appended claims.
[0017] Before the embodiments of the invention arc explained in
detail, it is to be understood that the invention is not limited to
the details of operation or to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention may be
implemented in various other embodiments and of being practiced or
being carried out in alternative ways not expressly disclosed
herein. Also, it is to be understood that the phraseology and
terminology used herein are for the purpose of descliption and
should not be regarded as limiting. The use of "including" and
"comprising" and variations thereof is meant to encompass the items
listed thereafter and equivalents thereof as well as additional
items and equivalents thereof. Further, enumeration may be used in
die description of various embodiments. Unless otherwise expressly
stated, the use of enumeration should not be construed as limiting
the invention to any specific order or number of components. Nor
should the use of enumeration be construed as excluding from the
scope of the invention any additional steps or components that
might be combined with or into the enumerated steps or
components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is an illustration of a touch sensor including
multiple electrodes for differential sensing techniques;
[0019] FIG. 2 is an illustration of a touch sensor including a
single electrode for capacitive sensing techniques;
[0020] FIG. 3 is a circuit diagram corresponding to the single
electrode touch sensor illustrated in FIG. 2;
[0021] FIG. 4 is a first timing diagram for the circuit of FIG.
3;
[0022] FIG. 5 is a second timing diagram for the circuit of FIG.
3;
[0023] FIG. 6 is a third timing diagram for the circuit of FIG.
3;
[0024] FIG. 7 is a fourth timing diagram for the circuit of FIG.
3;
[0025] FIG. 8 is a circuit diagram corresponding to the multiple
electrode touch sensor illustrated in FIG. 1;
[0026] FIG. 9 is a first timing diagram for the circuit of FIG.
8;
[0027] FIG. 10 is a second timing diagram for the circuit of FIG.
8;
[0028] FIG. 11 is a third timing diagram for the circuit of FIG.
8;
[0029] FIG. 12 is a fourth timing diagram for the circuit of FIG.
8;
[0030] FIG. 13 is an illustration of a touch sensor including an
active zone for determining proximity to a single electrode;
[0031] FIG. 14 is an illustration of a touch sensor including
multiple electrodes for time domain differential sensing;
[0032] FIG. 15 is an illustration of a touch sensor including a
single electrode for time domain differential sensing;
[0033] FIG. 16 is an illustration of finger approaching a touch
sensor including a single electrode and an activation zone;
[0034] FIG. 17 is a first graph illustrating voltage versus time
for the touch sensor illustrated in FIG. 16;
[0035] FIG. 18 is a second graph illustrating voltage versus time
for the touch sensor illustrated in FIG. 16;
[0036] FIG.. 19 is a third graph illustrating voltage versus time
for the touch sensor illustrated in FIG. 16;
[0037] FIG. 20 is a flow chart illustrating operation of the touch
sensor illustrated in FIG. 16;
[0038] FIG. 21 is a block diagram of a timing interface circuit for
the touch sensor illustrated in FIG. 16;
[0039] FIG. 22 is a touch sensor including an active zone for
determining if a stimulus (S) is greater than a proximity threshold
(X);
[0040] FIG. 23 is a circuit diagram for a touch sensor including
multiple electrodes and time domain differential sensing
circuitry;
[0041] FIG. 24 is a graph illustrating stimulus versus time for the
touch sensor illustrated in FIG. 23;
[0042] FIG. 25 is a graph illustrating rate of change of stimulus
versus time for the touch sensor illustrated in FIG. 23;
[0043] FIG. 26 is a circuit diagram for a touch sensor including
four electrodes and time domain differential signature processing
circuitry;
[0044] FIG. 27 is a depiction of four circular electrodes for use
with the touch sensor illustrated in FIG. 26;
[0045] FIG. 28 is a depiction of a ground plane for use with the
four circular electrodes depicted in FIG. 27 and the touch sensor
illustrated in FIG. 26;
[0046] FIG. 29 is a first illustration of a finger coming to rest
on a touch sensor including a single electrode;
[0047] FIG. 30 is a second illustration of a finder coming to rest
on a touch sensor including a single electrode;
[0048] FIG. 31 is a graph illustrating stimulus versus time for the
touch sensor illustrated in FIG. 26;
[0049] FIG. 32 is a graph illustrating rate of change of stimulus
versus time for the touch sensor illustrated in FIG. 26;
[0050] FIG. 33 is a depiction of a four non-circular electrodes for
use with the touch sensor illustrated in FIG. 26;
[0051] FIG. 34 is a depiction of a ground plan for use with the
four non-circular electrodes depicted in FIG. 33 and the touch
sensor illustrated in FIG. 26;
[0052] FIG. 35 is an illustration of a touch sensor including
multiple electrodes and an active zone for use with time domain
differential logic;
[0053] FIG. 36 is a circuit diagram of a multiple electrode touch
sensor including a time domain differential processing
circuitry;
[0054] FIG. 37 is a circuit diagram of a touch sensor including
eight single- or dual-electrode and time domain differential
processing circuitry;
[0055] FIG. 38 is a depiction of eight single-electrodes for use
with the touch sensor illustrated in FIG. 37;
[0056] FIG. 39 is a depiction of eight dual-electrodes for use with
the touch sensor illustrated in FIG. 37;
[0057] FIG. 40 is a depiction of twelve dual-electrodes for use
with the touch sensor illustrated in FIG. 37;
[0058] FIG. 41 is an illustration of a touch sensor including a
single electrode interposed between a flexible substrate and a
rigid substrate;
[0059] FIG.. 42 is an illustration of a finger approaching the
touch sensor illustrated in FIG. 41;
[0060] FIG. 43 is an illustration of a finger deflecting a flexible
substrate associated with the touch sensor illustrated in FIG.
41;
[0061] FIG. 44 is a graph illustrating stimulus versus time for the
touch sensor illustrated in FIGS. 41-43;
[0062] FIG. 45 is a graph illustrating rate of change of stimulus
versus time for the touch sensor illustrated in FIGS. 41-43;
[0063] FIG. 46 is an illustration of a touch sensor including a
single electrode interposed between two rigid substrates;
[0064] FIG. 47 is an illustration of a finger approaching the touch
sensor illustrated in FIG. 46;
[0065] FIG. 48 is an illustration of a touch sensor including a
sensor electrode and a biased electrode interposed between upper
and lower rigid substrates;
[0066] FIG. 49 is an illustration of a touch sensor including
multiple electrodes interposed between upper and lower rigid
substrates;
[0067] FIG. 50 is an illustration of a touch sensor including
multiple electrodes and a biased electrode interposed between upper
and lower rigid substrates;
[0068] FIG. 51 is a first graph illustrating stimulus versus time
for the touch sensor of FIGS. 49-50;
[0069] FIG. 52 is a first graph illustrating rate of change of
stimulus versus time for the touch sensor of FIGS. 49-50;
[0070] FIG. 53 is a second graph illustrating stimulus versus time
for the touch sensor of FIGS. 49-50;
[0071] FIG. 54 is a second graph illustrating rate of change of
stimulus versus time for the touch sensor of FIGS. 49-50;
[0072] FIG. 55 is a third graph illustrating stimulus versus time
for the touch sensor of FIGS. 49-50;
[0073] FIG. 56 is a third graph illustrating rale of change of
stimulus versus time for the touch sensor of FIGS. 49-50;
[0074] FIG. 57 is a fourth graph illustrating stimulus versus time
for the touch sensor of FIGS. 49-50;
[0075] FIG. 58 is a fourth graph illustrating rate of change of
stimulus versus time for the touch sensor of FIGS. 49-50;
[0076] FIG. 59 includes a circuit diagram for a single electrode
touch sensor including a filter function and time domain
differential signature recognition;
[0077] FIG. 60 includes a circuit diagram for a multiple electrode
touch sensor including a fitter function and time domain
differential signature recognition;
[0078] FIG. 61 illustrates a dual electrode touch sensor including
an inner electrode and an outer electrode;
[0079] FIG. 62 illustrates the dual electrode touch sensor of FIG.
61 including the net electric field;
[0080] FIG. 63 includes a first circuit diagram for the dual
electrode touch sensor illustrated in FIG. 61;
[0081] FIG. 64 includes a second circuit diagram for the dual
electrode touch sensor illustrated in FIG. 61;
[0082] FIG. 65 illustrates a dual electrode touch sensor including
spaced apart upper and lower rigid substrates;
[0083] FIG. 66 illustrates a dual electrode touch sensor including
spaced apart upper and lower rigid substrates and a biased lover
electrode;
[0084] FIG. 67 is an eight-electrode touch sensor employing
differential sensing techniques of the present invention;
[0085] FIG. 68 is a twelve-electrode touch sensor employing
differential sensing techniques of the present invention;
[0086] FIG. 69 illustrates a touch sensor including inner and outer
electrodes and a strobe electrode;
[0087] FIG. 70 is a circuit diagram of the touch sensor illustrated
in FIG. 69 and including a time differential processing
circuit;
[0088] FIG. 71 is a circuit diagram of the touch sensor illustrated
in FIG. 69 and including an inner buffer and first and second
stimulus and detection circuits;
[0089] FIG. 72 illustrates the touch sensor of FIG. 69 including
the net electric field;
[0090] FIG. 73 illustrates the touch sensor of FIG. 69 including an
overlying substrate supported by spacers;
[0091] FIG. 74 illustrates the touch sensor of FIG. 73 including
the net electric field;
[0092] FIG. 75 illustrates a first twelve-electrode sensor
including inner and outer electrodes;
[0093] FIG. 76 illustrates a lower strobe electrode for use with
the twelve-electrode sensor of FIG. 75;
[0094] FIG. 77 illustrates a second twelve-electrode sensor
including inner and outer electrodes;
[0095] FIG. 78 illustrates a lower strobe electrode for use with
the twelve-electrode sensor of FIG. 77;
[0096] FIG. 79 is a first side view of a touch sensor including
overlapping electrode rows and electrode columns;
[0097] FIG. 80 is a second side view of a touch sensor including
overlapping electrode rows and electrode columns;
[0098] FIG. 81 is a top view of the touch sensor of FIGS. 79-80
including electrode columns;
[0099] FIG. 82 is a top view of the touch sensor of FIGS. 79-80
including electrode rows;
[0100] FIG. 83 is a top view of the touch sensor of FIGS. 79-80
including electrode columns and electrode rows;
[0101] FIG. 84 is a circuit diagram of the touch sensor of FIG. 83
including a time domain differential signature processing
circuit;
[0102] FIG. 85 is a top view of the touch sensor of FIG. 83
depicting a column being driven and read in accordance with an
embodiment of the present invention;
[0103] FIG. 86 is a lop view of the touch sensor of FIG. 83
depicting a row being driven and read in accordance with an
embodiment of the present invention;
[0104] FIG. 87 is a top view of the touch sensor of FIG. 83
depicting a column and a row being driven and read in accordance
with an embodiment of the present invention;
[0105] FIG. 88 is a lop view of the touch sensor of FIG. 83
depicting multiple columns being driven and read in accordance with
an embodiment of the present invention;
[0106] FIG. 89 is a top view of the touch sensor of FIG. 83
depicting multiple rows being driven and read in accordance with an
embodiment of the present invention;
[0107] FIG. 90 is a top view of the touch sensor of FIG. 83
depicting multiple columns and rows being driven and read in
accordance with an embodiment of the present invention;
[0108] FIG. 91 is a first flow chart illustrating operation of the
touch sensor of FIG. 83 in accordance with an embodiment of the
present invention;
[0109] FIG. 92 is a flow chart continuing from the flow chart of
FIG. 91;
[0110] FIG. 93 is a second flow chart illustrating operation of the
touch sensor of FIG. 83 in accordance with an embodiment of the
present invention;
[0111] FIG. 94 is a flow chart continuing from the flow chart of
FIG. 93;
[0112] FIG. 95 is a circuit diagram of the touch sensor of FIG. 83
including a filter function and a time domain differential
signature processing circuit;
[0113] FIG. 96 is a first side view of the touch sensor of FIG. 83
illustrating a net electric field;
[0114] FIG. 97 is a second side view of the touch sensor of FIG. 83
illustrating a net electric field;
[0115] FIG. 98 is a circuit diagram for a circuit adapted to strobe
column electrodes and read row electrodes;
[0116] FIG. 99 is the circuit diagram of FIG. 98 modified to
include a stimulus selection circuit to route a response from a row
or column to a response detection circuit;
[0117] FIG. 100 is a top view of the touch sensor of FIG. 83
depicting the strobing of a single row and the reading of two
columns;
[0118] FIG. 101 is a top view of the touch sensor of FIG. 83
depicting the strobing of a single column and the reading of two
rows;
[0119] FIG. 102 is a top view of the touch sensor of FIG. 83
depicting the strobing of multiple rows and the reading of multiple
columns and vice versa;
[0120] FIG. 103 is a side view of a touch sensor including an
electrode column coupled to adjacent electrode rows;
[0121] FIG. 104 is aside view of a touch sensor including an
electrode row coupled to adjacent electrode columns;
[0122] FIG. 105 is a circuit diagram of the touch sensors of FIGS.
103-104 including a time domain differential processing
circuit;
[0123] FIG. 106 is the circuit diagram of FIG. 1OS modified to
include stimulus selection circuits to route a response from a row
or column to one of two detection circuits;
[0124] FIG. 107 is a top view of the touch sensor of FIGS. 103-104
depicting the strobing of a single column and the reading of
multiple rows;
[0125] FIG. 108 is a top view of the touch sensor of FIGS. 103-104
depicting the strobing of a single row and the reading of multiple
columns;
[0126] FIG. 109 is a top view of the touch sensor of FIGS. 103-104
depicting the strobing of multiple rows and the reading of multiple
columns and vice versa;
[0127] FIG.. 110 is a first side view of a touch sensor including
electrode columns and electrode rows;
[0128] FIG. 111 is the touch sensor of FIG. 110 modified to include
a flexible substrate;
[0129] FIG. 112 is a second side view of a touch sensor tad tiding
electrode columns and electrode rows;
[0130] FIG. 113 is the touch sensor of FIG. 112 modified to include
a flexible substrate;
[0131] FIG. 114 is a first side view of a touch sensor including
electrode columns and electrode rows and illustrating a net
electric field;
[0132] FIG. 115 is a second side view of a touch sensor including
electrode columns and electrode rows and illustrating a net
electric field;
[0133] FIG. 116 is a first side view of a touch sensor including
electrode columns, electrode rows, and a biased electrode;
[0134] FIG. 117 is the touch sensor of FIG. 116 illustrating a net
electric field;
[0135] FIG. 118 is a second side view of a touch sensor including
electrode columns, electrode rows, and a biased electrode;
[0136] FIG. 119 is the touch sensor of FIG. 118 illustrating a net
electtic field;
[0137] FIG. 120 illustrates a finger coming to rest against the
touch sensor of FIGS. 116-119;
[0138] FIG. 121 illustrates a stylus coming to rest against the
touch sensor of FIGS. 116-119;
[0139] FIG. 122 illustrates the net electric field for a touch
sensor including multiple electrode columns in the absence of a
touch input;
[0140] FIG. 123 illustrates the net electric field for a touch
sensor including multiple electrode columns and multiple electrode
rows in the absence of a touch input;
[0141] FIG. 124 illustrates the net electric field for a touch
sensor including multiple electrode rows in the absence of a touch
input;
[0142] FIG. 125 illustrates the net electric field for a touch
sensor including multiple electrode columns and multiple electrode
rows from a first side view;
[0143] FIG. 126 illustrates the touch sensor of FIGS. 123 and 125
being contacted by a stylus;
[0144] FIG. 127 illustrates the touch sensor of FIGS. 123 and 125
being deflected downwardly by a stylus;
[0145] FIG. 128 illustrates the touch sensor of FIGS. 123 and 125
being contacted by a finger;
[0146] FIG. 129 illustrates the touch sensor of FIGS. 123 and 125
being deflected downwardly by a finger;
[0147] FIG. 130 illustrates a light sensor array to determine the
position of an object above touch pads in accordance with
embodiments of the present invention;
[0148] FIG. 131 illustrates a light sensor matrix to determine the
position of an object above a touch sensor in accordance with
embodiments of the present invention; and
[0149] FIG. 132 illustrates the location of a fingertip in three
dimensions relative to the touch sensor of FIG. 131.
DETAILED DESCRIPTION OF THE CURRENT EMBODIMENTS
[0150] The invention as contemplated and disclosed herein includes
systems and methods for detecting one or more touch inputs. The
systems and methods include monitoring a rate of change of
capacitance to determine when an object comes to rest against a
substrate. Part I includes an overview of time domain differential
sensing techniques. Part II relates to single electrode and
multiple electrode touch sensors employing tune domain differential
sensing techniques. Part III relates to matrix electrode touch
sensors employing tune domain differential sensing techniques.
Lastly, Part IV relates to time domain differential sensing in
light sensors, optionally for use in conjunction with the touch
sensors discussed in Parts II-III.
I. Overview of Time Doman Differential Sensing
[0151] International Patent Application W02010/111362 to Caldwell
et al, filed Mar. 24, 2010, the disclosure of winch is incorporated
by reference in its entirety, describes many deficiencies and
limitations associated with projected capacitance, capacities and
differential sensing, as well as techniques for overcoming such
deficiencies and limitations. These very techniques when properly
applied can yield more opportunities for greater performance and
additional features than can be achieved from existing capacitance
and field effect sensing techniques that are based solely on
predetermined threshold values.
[0152] In particular, International Patent Application
W02010/111362 describes using a single electrode and "Time Domain
Differential" sensing techniques to achieve more reliable touch
sensing by actually sensing the "signature of a touch". The Time
Domain Differential sensing techniques can initially use the same
techniques as described for detecting the touch signal Vs in FIG. 3
(and for that matter, Vs in FIG. 8 when using a multi-electrode
sensor). The basic description of a touch by a human as it moves
towards a surface above a given singular electrode that stops the
finger and therefore physically limits the finger approach to the
sensing electrode and therefore limits the amount of stimulus that
can be sensed by the sensing electrode. The signature of a touch
event caused by a human finger is then defined by first determining
if the finger is in proximity of the sensing electrode by
approaching with the Active Zone shown in FIG. 13 where the
stimulus (s) would be greater than a loosely set value of x. Once
it is determined that the finger is within proximity to the sensing
electrode and is within the Active Zone as indicated by s>x.
then the rate of change of stimulus with respect to time (ds/dt) is
determined and analyzed. The rate of change of stimulus is
described as a stimulus change caused by a human finger approaching
the touch surface/fascia over a cmTesponding sensing electrode or
electrodes with respect to time.
[0153] There are numerous techniques for generating and sensing the
stimulus used in detecting a touch such as described earlier,
including both self-capacitance techniques involving a single
electrode and mutual-capacitance techniques involving two or more
electrodes. Even though depending on the technique used to generate
and detect a stimulus based on a touch input can cause the stimulus
to increase or decrease as the touch input approaches the touch
surface let us assume the stimulus increases as a finger or other
appendage/device approaches a touch surface interface (this may
happen naturally, based on the sensing technique, or can be
fotmatted by inversion, etc), whether a single or multi-electrode
sensor. Therefore the basic definition of a touch signature,
processed with analog/digital hardware or software, or a
combination of both would be defined by the basic logical sequence
of events of 1) if the stimulus (s) changes and is detected, based
on the finger/appendage or other touch input device in close
proximity to the sensing electrode, is greater than some value
(s>x) followed by: 2) the stimulus rate of change with respect
to tune (ds/dt), based on the finger moving towards the touch
sensing electrode, is greater than zero (ds/dt>0) followed by:
3) the stimulus rate of change with respect to time, caused by the
finger coming to rest above the sensing electrode being stopped by
the surface fascia (ds/dt=O or very close to 0 relative to the
ds/dt when the finger is moving) then if conditions arc such that
event 1 is true and event 2 is true and event 3 is true, then the
process will indicate there is a touch stimulus.
[0154] It should be noted that there ate no absolute values that
have been predetermined for the process of evaluating a touch. As
an example therefore, if a glove were to be worn on the finger,
adding additional layers of thickness; preventing the finger from
actually touching the touch surface and essentially adding distance
(the distance generally based on the thickness of the glove) then
as long as the stimulus is in proximity above the sensing
electrodes (s>x which is condition 1 above) and when conditions
2) and 3) are met above, then a touch would be detected just as
when a non-gloved finger/appendage is used. Implementing the above
logical conditions results in the consistent touch "feel" sensing
of a touch using gloved or non-gloved conditions. In addition
should the substrate dielectric, substrate thickness, or other
manufacturing tolerances cause the effective stimulus strength to
vary, using the above logical sequence to detect the touch input
will allow a consistent "feel" of the touch response as compared to
using a predetermined threshold as used in conventional capacitance
and differential sensing methods of which both use a predetermined
threshold that correspond to the stimulus response and the touch
signal response.
II. Single Electrode and Multi Electrode Touch Sensors
[0155] Time Domain Differential sensing techniques can be
implemented with single and multiple electrode touch sensors. These
techniques can be used to determine a touch signature using a
single electrode or multiple electrodes based on s, ds, S dS, t,
dt, T, dT, ds/dt, ds/dT, dS/dt, dS/dT, where s (or S, where
s<<S) represents the absolute value of the electrode
capacitance and t and Tare time domains, where t<<T. These
techniques can also be used to determine a touch signature using
two electrodes. FIG. 14 illustrates a multi-electrode sensing
structure and FIGS. 13 and 15 illustrate a single-electrode
structure. Regardless of the sensing technique the stimulus
response to a finger/appendage or other touch input device
approaching the touch surface can be analyzed according to the
plinciples described above. FIG. 16 is a drawing from International
Patent Application W02010/111362 which illustrates a touch input in
the form of a finger as it approaches a single electrode and FIG.
17 illustrates the stimulus as well as a rate of change of that
stimulus as it CoiTesponds to the finger approaching the single
electrode. The response in FIG. 17 may also illustrate the response
of a multiple electrode sensor and detecting circuit Likewise the
FIGS. 18, 19, 20, and 21 could apply to a multiple electrode
response
[0156] Refer again to FIG. 13. Assume the stimulus sensing method
of touch increases as the finger approaches the substrate top
surface 112. The logic for detecting the touch is defined by the
sequence of events based on proximity and the rate of change of
stimulus with respect to time as a human finger approaches the
defined touch surface 112 above a singular electrode 100 or
multiple electrodes 100, 104. This definition is implemented to
mimic the same response as a simple switch, but as applied to touch
sensing In actuality the signatme for touch could be redefined. For
instance, a simple example would be the signature that is defined
above with the addition of new condition where a 4th condition
needs to be followed by a negative ds/dt. If the first three
sequences are met then the condition ds/dt<0 will be a
terminating condition (the finger needs to be removed sometime
which will result in a ds/dt<0).
[0157] Assuming s increases as a finger moves towards the touch
surface 112 and s represents the touch stimulus, then for a
"Conventional touch" the sequence for processing a touch would be
as has been described above:
[0158] 1) If s>x (proximity threshold) [0159] and
[0160] 2) ds/dt>0, followed by
[0161] 3) ds/dt=0, then
[0162] 4) touch is detected
[0163] Adding the new condition where the ds/dt<0 is required to
for a touch to be detected which we might call "touch on release",
then the following sequence would be as follows:
[0164] 1) If s>x (proximity threshold) [0165] and
[0166] 2) ds/dt>0, followed by
[0167] 3) ds/dt=0, followed by
[0168] 4) ds/dt<0, then
[0169] 5) touch is detected
[0170] The first step above may not be needed, depending on the
stimulus detecting technique. In the above desclibed logical
sequence of conditions, the first step serves as a gatekeeper to
the recognition for touch. Using less robust sensing techniques in
order for the steps 2 through 5 to be completed the stimulus needs
to meet a level of signal strength to be valid. This eliminates the
processing of signals and noise that mas not be a valid touch
stimulus. Other means may be used to discern valid stimulus
strength and presence. One example would be the use of multiple
electrode structures and associated stimulus sensing techniques for
differential sensing which would tend to reduce or reject common
mode noise. Eliminating or reducing the noise signature might allow
the elimination of Step 1 in the both logical sequences described
above.
[0171] Note that regardless of whether using a single or multi
electrode pad design, by changing only the definition of the touch
signature (by adding step condition 4) the touch response would be
different. Note also that by adding step 4 above did not involve
changing a predetermined threshold. Also note that the logic for
determining the touch response is embedded in the definition of the
touch sensing inherently. In existing capacitance, projected
capacitance, and differential sensing techniques, the first
response would be the detection of s>x as the touch response
without regard to the ds/dt and related sequences. In the case
where the touch response is dependent on a predetennined threshold
the result would be regarded as a proximity effect which is the
first step in the above examples. As an example of the effect on
the sensing, a bare finger and a gloved finger would react equally
once s>x, especially for a "conventional touch". "Touch on
release" using conventional capacitance, projected capacitance, and
differential sensing techniques would be implemented by adding an
additional step to the "s>0" step, where the stimulus inserted
by the finger would drop below some value (s<x2 or s<x). Of
course, similar to the condition when s>x the "touch on release"
using conventional capacitance, projected capacitance, and
differential sensing techniques would have similar responses
regarding a bare finger as compared to gloved finger as in either
case the finger is moved from the sensor surface Comparative
sequences for capacitance, projected capacitance, and differential
sensing techniques might look as follows.
[0172] Assuming s increases as a finger moves towards a touch
surface and s represents the touch stimulus, then for a
"Conventional touch" using conventional capacitance, projected
capacitance, and differential sensing techniques generally would be
as described above:
[0173] 1) If s>x (proximity threshold), then
[0174] 2) touch is detected.
Adding the new condition where the s<x is required for a touch
to be detected using capacitance, projected capacitance, and
differential sensing techniques which we might call "touch on
release", then the following sequence would be as follows:
[0175] 6) If s>x (proximity threshold), followed by
[0176] 7) s<x (or x2), then
[0177] 8) touch is detected
Note again, in the above described sequences there is not a
condition dependent on the use of ds/dt.
[0178] One potential additional distinction of time domain
differential sensing as compared to conventional capacitance
systems is that time domain differential can use faster sample
rates as compared to conventional capacitance. Capacitance
measuring techniques are not inherently dependent on time. As long
as the stimulus exceeds a predetermined threshold level (s>x)
and the sensing interface is capable of measuring this change in
the stimulus, then in principle the interlace needs to only take
simply two samples. As an example, for the perception to a user
that a touch system will respond instantly, a touch interface
system would need to respond around 30 milliseconds. Based on
sampling theorem, the system would have to sample at twice the
frequency of the response required which would mean that the
sensing interface would have to respond to a touch stimulus in 15
milliseconds. A conventional capacitance system would have to
measure the stimulus or a change in stimulus, compare that stimulus
or change of stimulus (therefore s=stimulus or change in stimulus)
to a threshold value (s>x, assuming s increases as the finger
moves towards the touch surface), if this comparison to x is true
within 15 milliseconds, then the response will only require one
sample in 15 milliseconds and at most 2 samples in 30 milliseconds.
This is quite doable in a variety of ways.
[0179] In comparison, time domain differential sensing techniques
use multiple measurements in the same time domain of 15 ms to
calculate the number of ds/dt values as needed to analyze the
proper sequence that defines the touch detection. Time domain
differential sensing can require measuring the stimulus s many
limes in the same time domain (30 milliseconds, see FIG. 18) in
order to capture the conditions ds/dt>0, ds/dt=0, ds/dt>0,
etc. Therefore the time domain differential will typically, though
not always, use higher sampling rates. This additional processing
speed may necessitate additional electronic circuitry or more
processing speed in a microprocessor or both as compared to a
typical capacitance touch sensor. Again, time domain differential
sensing does not depend on a precise predetermined threshold value
to detect a touch and relies on the evaluation of ds/dt as part of
the decision pmcess for determining whether a touch is present or
not unlike capacitance or differential which predominately make its
decision on a predetelmined threshold value.
[0180] Time domain differential sensing techniques initially
measure the same parameters as capacitance, projected capacitance,
and differential sensing techniques, including time. By using time
domain differential sensing techniques and the other parameters
that are available (such as s and time) new sensing features that
were otherwise unavailable when using conventional capacitance
sensing interfaces become available. These other parameters become
very useful when the time domain differential interface detelmines
if there is a touch and then uses these parameters. Interesting
possibilities raise when a time domain differential interface can
evaluate the values of s and time after a touch is detected. The
possibilities of multiple touch points or gestures over a single
touch surface become possible utilizing n time domain differential
interface. As an example if the following sequence were to be
allowed to be met by changing the physical structure of a touch
input then there could be at least two touch conditions:
[0181] 1) If s>x (proximity threshold) [0182] and
[0183] 2) ds/dt>0, followed by
[0184] 3) ds/dt=0, then
[0185] 5) touch #1 [0186] and if followed by
[0187] 6) ds/dt>0, followed by
[0188] 7) ds/dt=0, then
[0189] 8) touch #2 is detected
[0190] FIG. 13 illustrates a basic single electrode touch sensor
with an Active Zone where the basic time domain differential logic
can be applied to in which a simple switch function could be
replaced. FIG. 23 illustrates a touch detecting circuit, which
would be the same as the detecting circuit in FIG. 3 with the
exception that the Predetermined Threshold Processing Circuitry 108
is replaced with a Time Domain Differential Processing Circuitry
114, with detecting elements Cs, Ce, control devices A, B, C, and
Analog to Digital Converter 106 where the output of said Analog to
Digital Converter is called the Stimulis (S) and is output to the
Time Domain Differential Processing Circuitly 114. The Time Domain
Differential Processing Circuitry 114 can be analog, digital, or
software processing, optionally substantially as set forth in
International Patent Application W02010/111362. FIGS. 24 and 25 are
timing charts for S and dS/dt as they relate to the time Domain
Differential processing sequence. Assume that the value Stimulus
(S) is formatted to increase in value as the touch stimulus is
applied (i.e. as the finger/appendage or oilier touch input deuce
approaches the touch surface). Stimulus (S) at tO is represented as
a base level of 1.00 at the "no touch" condition when a
finger/appendage stimulus is far away from the touch surface. The
rate of change of S relative to time at tO (dS/dt) is represented
as abase level of 3.00 at the same "no touch" condition described
above. At time t1 stimulus S is detected as increasing. At time t1
the dS/dt is detected at a value which would proportional to the
rate of change of S with respect to time which is in this case is a
value of 4.00. The HI ds/dt reference value of 5.00 and the LO
ds/dt reference value of 1.00 are used as a filter. If the touch
input stimulus is affected by other factors such as electrical
noise (much faster than which a touch stimulus would be) or
temperature (much slower than touch stimulus would be) then the
processing circuitry which can be implemented in hardware or
processed in software or a combination of both can discriminate
against these other factors which cannot be a touch based on the
response time of the touch signature. As an example, if electrical
noise were to cause the stimulus to increase at a rate that cannot
be a touch input then the processing circuitry would detect this in
by generating a positive high dS/dt or a negative high ds/dt value,
both of which may be indicative of rate of stimulus insertion or
extraction that a human could not possibly accomplish. In this case
the processing circuitry or software could ignore, attenuate,
interpolate, the dS/dt and/or S. In all cases the processing
circuitry would not falsely indicate a touch condition. Similarly,
if the rule of change of stimulus insertion $ were to be too slow,
the processing and/or software would ignore, attenuate, interpolate
the dS/dt and/or S. If a finger were to approach at a rate that is
far slower than what a finger would normally approach the touch
surface or if temperature were to cause a stimulus change that is
even slower rate, the processing circuitry and/or software logic
would ignore, extrapolate, etc. the dS/dt and/or S. In both cases
the touch processing circuitly would not result in the
interpretation of a valid touch input.
[0191] Referring to FIGS. 24 and 25 again, it can be easily be seen
the information available for a valid touch. At time tO the
stimulus S Is at a base value of 1.00 which corresponds to no
stimulus. Also at time tO the dS/dt is at a base value of 3.00
which corresponds to no rate of change of Stimulus S with respect
to time t. At time t1 the stimulus S starts to increase as shown in
FIG. 24 and simultaneously the rate of change of stimulus S with
respect with timet (dS/dt) is a value of 4.00 (a rate dS/dt of 1.00
which is added to the base value of 3.00 which will yield a net
value of 4.00). The stimulus continues to increase until the
finger/appendage comes into contact with the surface at time t3,
stopping the approach and therefore the stimulus insertion. If the
finger/appendage were to immediately, upon touching the touch
surface, strut to move away from the touch surface, the amount of
stimulus S would start to decrease. Therefore simultaneously at
time t3 the dS/dt would immediately go to a negative value. This is
shown as a value of 2.00 (a rate of change of 1.00 which is added
to the base of 3.00 which will yield a net value of 2.00). The
stimulus S will continue to decrease as the finger/appendage moves
farther from the touch surface (and therefore the sensor electrode)
until the finger/appendage is far enough away from the sensor
electrode such that the "no condition" of S=3.00 and the "no
condition" of dS/dt=3.00 is met at time t5. If at time t3 the
finger/appendage were to rest on the surface, then the stimulus
value of S would stay at 3.00 but the dS/dt value at time t3 would
go to zero. Of course from time t1 to time t3 the stimulus S will
exceed the Active Zone set point of 1.50 between time t1 and time
t2. The logic for a simple touch could therefore be:
[0192] 1) if S>x (1.50) (ActiveZone set point=x (1.50)) [0193]
and
[0194] 2) dS/dt>Lo dS/dt (3.50) and dS/dt<+Hi dS/dt (4.50)
followed by
[0195] 3) ds/dt 0, then
[0196] 4) touch is detected (therefore at time t3)
The effective result of this would be that the finger/appendage
would have to simply come in contact with the touch surface
(whether weruing a glove or not. etc.) before a touch would be
considered valid. Alternatively for a simple touch the logic for
valid touch could be:
[0197] 1) If S>x (1.50) (ActiveZone set point=x (1.50)) [0198]
and
[0199] 2) dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dtl (4.50)
followed by
[0200] 3) S<x (1.50), then
[0201] 4) touch is detected (therefore at time t4.5)
[0202] The effective result of this would be that the
finger/appendage would have to be pulled away far enough to be
outside of the Active Zone before a touch would be considered
valid. And yet another alternative for valid touch logic could
be:
[0203] 1) If S>x (1.50) (Active Zone set point=x (1.50)) [0204]
and
[0205] 2) dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt (4.50)
followed by
[0206] 3) ds/dt<x (1.50), then
[0207] 4) touch is detected (therefore at time t4.5)
The effective result of this would be that the finger/appendage
would have to be pulled away from the touch surface to be
considered be considered valid.
[0208] Refer to FIGS. 26, 27, and 28. FIG. 26 extends the concept
of measuring a singular single sensor to multiple single sensors.
Shown in FIG. 26 are a total of four single sensors depicted as
Ce1, Ce2, Ce3, and Ce4, each with a control device (control devices
1, 2, 3, and 4) for connecting each single sensor to the sampling
capacitor Cs. The sequence for each sensor would be the same as
described above or otherwise. FIGS. 27 and 28 show a four sensor
layout that would work with processing circuit shown in FIG. 26. An
optional dielectric layer can be interposed between the electrodes
100 of FIG. 27 and the ground plane of FIG. 28.
[0209] Other features can be implemented using the techniques of
Time Domain Differential touch sensing by changing the definition
and possible the electrode structure. Refer to FIGS. 26, 29, 30,
31, and 32. FIGS. 29-30 depict a single electrode sensor similar to
what has been described and a finger approaching the touch surface
(the finger could be another appendage or touch input device) and
coming to rest at the surface of the touch surface. This sequence
is detected by the detection and processing circuitry in FIG. 26
and the stimulus (S) is and dS/dt are shown from time t1 through t3
on FIGS. 31 and 32 and represents the sequence for a simple touch.
If at time t2 the finger were to be "rolled" such us to flatten the
finger, causing more surface area coupling from the finger to the
sensor electrode on the bottom surface of the touch substrate, then
the stimulus S would continue to increase to a higher level as well
as causing a jump in dS/dt while the finger is moving. After the
movement, the finger comes to rest again. This sequence is seen
from time t3 to t5. This would indicate a second state. Each set of
sequences cold be treated as an individual touch event or any
combination of these sequences together could be interpreted as a
touch event. These different combinations might be called a "touch
signature." The above sequence could be described as follows:
[0210] 1) If S>x (1.50) (ActiveZone set point=x (1.50))
[0211] and
[0212] 2) dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt (4.50)
followed by
[0213] 3) dS/dt returns to 0 then
[0214] 4) touch #1 is detected (at time t2)
[0215] 5) If touch #1 is not reset (NOT back to "no touch" state)
then
[0216] 6) If dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt
(4.50) followed by
[0217] 7) dS/dt returns to 0 then
[0218] 8) touch #2 is detected (at time t4)
[0219] FIGS. 33 and 34 illustrate a multiple touch input layout
that could use the above described sequence. Note each touch sensor
116 includes an electrode comprising two intersecting circles 118,
120. Each circle 118, 120 is sized to be approximate the size of a
finger flattened out. This will optimize and limit the amount of
finger coupling to the sensor when a finger touches the glass
surface during a n0lmal touch. If a person were to touch above the
circle farthest away from the trace connection "the top circle",
this would be registered as touch #1. If the finger were to then be
rolled (separated by step 3 of dS/dt returns to zero) then the
bottom circle allows the finger to increase its capacitive coupling
to the sensor allowing for the detection of touch 2. Other
electrode configurations having in egular or discontinuous outer
peripheries are also possible. This illustrates that the touch
electrode design can be modified to enhance the "touch signature"
response. The electrode structure cad be enhanced to help filter
out unwanted stimulus S.
[0220] FIG. 35 illustrates a multi electrode touch sensor with an
Active Zone where such as would be used in capacitance sensor as in
FIG. 1. The basic time domain differential logic can be applied to
in which a simple switch function could be replaced FIG. 36
illustrates a touch detecting circuit, which would be the same as
the detecting circuit in FIG. 8 with the exception that the
Predetermined threshold Processing Circuitry 108 is replaced with
Time Domain Differential Processing Circuitry 114, with detecting
elements Cs. Ce, control devices A and C, Output Dlive B, and
Analog to Digital Converter 106 where the output of said Analog to
Digital Converter 106 is called the Stimulis (S) and is output to
the Time Domain Differential Processing Circuitry 114. This type of
detecting circuit with its associated dual electrode approach can
be more water immune by ignoring stimulus S that go in the opposite
direction as a touch stimulus S. The stimulus S would tend to go in
the opposite direction for water laying on the touch surface above
the dual electrode sensor area. All of the techniques described in
processing the stimulus S and rate of change of stimulus with
respect to time dS/dt can be used to process the output associated
with FIGS. 35 and 36. Also, the concept of measuring the response
of multiple dual electrode sensors with common processing circuitry
can be applied. One particular configuration would be that that
shown in FIG. 37. FIG. 37 illustrates a multiple input
configuration with eight dual electrode sensors as described in
FIGS. 35 and 36. Each sensor is represented by the net effect
capacitance of Ce1, Ce2, Ce3, Ce4, Ce5, Ce6, Ce7, Ce8 and each has
a control device (1-8) for connecting/isolating to/from the
sampling capacitor Cs and associated processing circuitry. Ce1
through Ce2 are shown in this example that all sensors are driven
by Output Drive B via one common drive line and Output Drive D via
a second common dliveline. FIG. 38 specifically would apply to FIG.
37. Other configurations that are possible using similar techniques
are shown via layouts in FIG. 39 and FIG. 40. The layout in FIG. 40
is optimized for immunity by enhancing the coupling from the outer
electrode 104 to the inner electrode 100 in each sensor location.
The enhanced coupling is accomplished by increasing the linear
length of the outer perimeter of each outer and inner conductive
pad 100, 104 where they are adjacent each other while maximizing
the amount of pad area to increase the coupling through water from
the outer to the inner pad. This will maximize the size of the
stimulus if water were to lay on the touch surface 112 over the
particular sensing electrode structure allowing a greater stimulus
S. A greater stimulus caused by water (in the opposite direction of
a touch stimulus) allows the processing circuitry to more easily
discriminate against water versus a touch stimulus.
[0221] Referring to FIG. 41, note the addition of an extra
dielectric layer 122 in the form of a flexible substrate that is
separated by the first dielectric substrata 102 in the fmm of a
rigid substrate. The separation can be implemented and maintained.
In a variety of ways and the material between the dielectic
flexible substrate 122 and rigid substrate 102 can be a vadety of
constructions including air FIG. 42 illustrates separation and
support between the flexible and dgid substrates 122, 102 by
spacers 124. The purpose of the spacers 124 is to support and
maintain air gap spacing between the flexible and rigid substrates
122, 102. Note that the additional dielectlic material and
associated air gap are located with the Active Zone. FIGS. 41-43
illustrate the function of the structure of the three dimensional
sensor using the Time Domain Differential sensing technique. FIG.
42 illustrates a finger/appendage in contact with the touch surface
112 of the dielectric flexible substrate 122. This would create a
first "touch event" FIG. 45 illustrates a finger/appendage in
contact with the touch surface 112 of the dielecuic flexible
substrate 122 and where the finger appendage is applying enough
physical pressure to depress and bend the dielectric flexible
substrate 122 so as to decrease the distance and increase the
dielectric constant between the finger/appendage touching the top
side of the dielectric flexible substrate 122 and sensor electrode
100 on the top or bottom side of the rigid substrate 102.
[0222] FIGS. 44 and 45 illustrate a liming diagram tor die
operation of the sensor Structure in FIGS. 42 and 43. One basic
implementation of the sensor structure might be as follows: from
time tO to t1 the stimulus, S, and the rate of change of S with
respect to time, dS/dt, are both at the "no touch" condition (a
base value of 1.00 for S and a base value of 3.00 for dS/dt). From
t1 to t2, as the finger/appendage approaches the touch surface on
the upper side of die flexible surface, as shown in FIG. 42, S
increases until the finger is limited by the touch surface at t2, a
value of 2.00. Accordingly, from t1 to t2 the dS/dt is at a value
of 4.00, indicating a rale of change of S with respect to time. At
t2, when the finger/appendage stops at the touch surface, dS/dt
returns to the base value of 3.00. This sequence of events could be
processed as a valid touch event. From t2 to t3 the
finger/appendage is in contact with the touch surface and the
stimulus S is at a value of 2.00. Simultaneously, there is no
change in the stimulus with respect time, and therefore dS/dt is at
base value of 3.00 (no change). From t3 to t4 the finger/appendage
applies pressure causing the flexible substrate to bend, decreasing
the distance and increasing the dielectric constant (by displacing
the air with the flexible substrate matelial) between the
finger/appendage and the sensor electrode on the bottom side of the
rigid substrate. This action will cause the stimulus S to increase.
This is shown in FIG. 44 as the stimulus S increasing from a value
of 2.00 to 3.00 from t3 to t4. Simultaneously, there will be a jump
in dS/dt as shown in FIG. 45. The value of dS/dt is shown as a
value of 4.00 from t3 to t4. At t4 when the finger/appendage stops
increasing the deflection of the Flexible substrate, the stimulus S
stops increasing and is shown in FIG. 44 as stopping at a value of
3.00. Simultaneously at t4, dS/dt returns to "no change" as
indicated at the base value of 3.00. This sequence of events could
be processed as a touch event. From t4 to t5 there is no change in
stimulus insertion by the finger/appendage and FIGS. 44 and 45 show
this state as described above. From t5 to t6 the finger/appendage
would be removed from the touch surface outside of the Active Zone.
The stimulus S drops to the "no touch" state with a simultaneously
negative (-dS/dt) of a value of 1.00 (base value of
3.00+(-2.00)=1.00). At t6 the sensor is in a "no touch" state and
the S and dS/dt return to their base "no touch" states of 1.00 and
3.00 respectively.
[0223] The construction of the touch sensor shown in FIGS. 42 and
43 coupled with tone domain differential sensing techniques
described above can yield new feature; while maintaining the
consistency of proper "feel" of touch despite the many variables
that may be introduced that would normally plague conventions
capacitance and differential sensing techniques that utilize a
predetermined threshold. This construction could be considered a
basic thee dimensional touch sensor as there can be at least one
and then two responses for a given touch location on the touch
surface. Referring to FIGS. 41 through 45. again die sequence of
logical steps might be:
[0224] 1) if S>x (1.50) (ActiveZone set point=x (1.50)) [0225]
and
[0226] 2) dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt (4.50)
followed by
[0227] 3) dS/dt returns to 0 then
[0228] 4) touch #1 is detected (at time t2)
[0229] 5) If touch #1 is not reset (NOT back to "no touch" state)
then
[0230] 6) If dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt
(4.50) followed by
[0231] 7) dS/dt returns to 0 then
[0232] 8) touch #2 is detected (at time t4)
The effective result of this would be detection of two distinct
touches in sequence. Also the above did not depend on a
predetermined threshold level other than the loosely defined
setpoint for the Active Zone. Alternatively, and referring to FIGS.
41 through 45, the following logical sequence of conditions would
yield the same results as the previous example but perhaps with
somewhat higher reliability based on adding additional conditions
from data available to the processing circuitry:
[0233] 1) If S>x (1.50) (ActiveZone set point=x (1.50)) [0234]
and
[0235] 2) dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt (4.50)
followed by
[0236] 3) dS/dt returns to 0 then
[0237] 4) touch #1 is detected (at time t2); Remember value of S
(S1=S)
[0238] 5) If touch #1 is not reset (NOT back to "no touch" state)
then
[0239] 6) If dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt
(4.50) followed by
[0240] 7) dS/dt returns to 0 and (5>2.75) then
[0241] 8) If S>S1 then
[0242] 9) touch #2 is detected (at time t4)
The effective result of this would be detection of two distinct
touches in sequence. Also even though the processing circuitry
evaluates the stimulus S, still a predetermined threshold is not
used but two valiable values of S are obtained and compared to each
other.
[0243] Yet another alternative would be the following logical
sequence of conditions that could yield the same results but with
perhaps higher reliability based on infmmation available to the
processing circuitry:
[0244] 1) If S>x (1.50) (Active Zone set point=x (1.50)) [0245]
and
[0246] 2) dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt (4.50)
followed by
[0247] 3) dS/dt returns to 0 and (S>1.75 and S<2.25) then
[0248] 4) touch #1 is detected (at time t8)
[0249] 5) If touch #1 is not reset (NOT back to "no touch" state)
then
[0250] 6) If dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt
(4.50) followed by
[0251] 7) dS/dt returns to 0 and (S>2.75) then
[0252] 8) touch #2 is detected (at time t4)
The effective result of this would be detection of two distinct
touches in sequence. Also even though the processing circuitry
evaluates the stimulus S, still a predetermined threshold is not
used (but two separate ranges arc evaluated).
[0253] Refer to FIGS. 42 through 43 and specifically FIGS. 44 and
45. Time t7 to t14 illustrate a way to show a linear sensing based
on increasing deflection from increasing pressure by a
finger/appendage on die top surface of the flexible substrate FIG.
44 illustrates stimulus S is increased in a series of steps by
applying the finger/appendage to the lop surface of the flexible
substrate and then applying increasing pressure and therefore
defied ion of the flexible substrate. FIG. 45 illustrates the
sequence of increased pressure and therefore deflection in discrete
steps by four alternating pulses of dS/dt. An example of the
processing of a sequence of events might be as follows:
[0254] 1) If S>x (1.50) (ActiveZone set point=x (1.50)) [0255]
and
[0256] 2) dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/di (4.50)
followed by
[0257] 3) dS/dt returns to 0 then
[0258] 4) touch #1 is detected (at time t8). Remember value of S
(S1=S)
[0259] 5) If touch #1 is not reset (NOT back to "no touch" state)
then
[0260] 6) If dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt
(4.50) followed by
[0261] 7) dS/dt returns to 0 and (S>S1) then
[0262] 8) touch #1 is detected (at time t10) Remember value of S
(S1=S)
[0263] 9) If touch #1 is not reset (NOT back to "no touch" state)
then
[0264] 10) If dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt
(4.50) followed by
[0265] 11) dS/dt returns to 0 and (S>S1) then
[0266] 12) touch #3 is detected (at time t12) Remember value of
S(S1=S)
[0267] 13) If touch #1 is not reset (NOT back to "no touch" state)
then
[0268] 14) If dS/dt>+Lo dS/dt (3.50) and dS/dt<+Hi dS/dt
(4.50) followed by
[0269] 15) dS/dt returns to 0 and (S>S1) then
[0270] 16) touch #4 is detected (at time t14) Remember value of S
(S1=S)
[0271] FIGS. 46 and 47 illustrate an alternative construction to
that of FIGS. 42 and 43. FIGS. 46 and 47 illustrates a construction
of two rigid substrates 102, 122 separated by collapsible spacers
124 that will allow for the decreasing distance/increasing average
dielectric constant between the finger/appendage on the lop touch
surface 112 of the upper rigid substrate 122 and the sensor
electrode 100 on the top or bottom side of the lower rigid
substrate 102. FIG. 48 is similar to the construction of the sensor
in FIG. 41 with the two exceptions: 1) the sensor electrode 100 is
located and attached on the bottom side 126 of the upper flexible
substrate 122 and 2) an additional electrode 128 is located on the
top side 130 of the lower rigid substrate 102. The additional
electrode 128 is biased at ground potential, and can also be
located on the bottom side of the upper rigid substrate 122. The
ground allows for the change of Stimulus in that it emulates the
finger/appendage as the flexible substrate moves toward (but not
touching) the grounded biased electrode 128. The time domain
differential techniques described above can be implemented with all
of the structures illustrated in FIGS. 41 through 42, 43, 44, 47,
and 48.
[0272] FIGS. 49 and 50 show similar configurations similar to those
shown in FIGS. 41 through 48 but with multi-electrode structures as
described so far and other similar structures. The upper substrate
122 where the top touch surface 112 is located can be made of
cither flexible or rigid substrates as long as the techniques
described in the physical construction and operation of FIGS. 41
through 48 are applied, again with the exception that
multi-electrode techniques are employed. All of the detecting and
processing techniques utilizing Time Domain Differential detecting
and processing techniques can be applied with the structures in
FIGS. 49 and 50 as well as their activations also. In addition, the
sensing electrode 100 is depicted as being positioned on the
underside of the upper rigid substrate 122, while the biased
electrode 128 is depicted as being positioned atop the lower rigid
substrate 102. In other embodiments, however, the sensing electrode
100 is positioned atop the lower ligid substrate 102 and the biased
electrode 128 is positioned on the underside of the upper rigid
substrate 122.
[0273] Combining different sequences utilizing the techniques of
detecting S and dS/dt as described above may be used to create
other user input features. These user features can enhance the
utilitarian function of a touch input function. FIGS. 51/52, 53/54,
and 57/58 illustrate some of the variety of sequences that could be
employed that would equate to a variety of specific output
functions. As by example:
[0274] FIGS. 51152 illustrate a sequence of events that would
basically mean that as a touch input stimulus is brought to the
surface of without depressing, then pressing further, followed by a
light touch, then depressing, then light touch, then a final
depressing might indicate a function. Likewise, a light depression,
followed by a depressing might select a certain function whereas
the next depression might select a sub-function, followed by a
light touch and next depression would be a second sub-function.
[0275] FIGS. 53/54 illustrates at the same touch input location as
FIGS. 51/52 that if a touch stimulus were to touch and depress
immediately the touch input and perhaps above the S value of x2 (a
dS/dt accompanied by a S value>x2), then the function would be a
different function followed by a sub-function value when there is a
light touch followed by a second depression
[0276] FIG. 55/56 illustrates at the same touch point as descdbed
in FIGS. 51152 and 53/54 but a different set of conditions in this
set of sequences the after the initial depression and first action
(dS/Dt accompanied by a S value>x2) followed by a pedod of time,
then two sub-function selections based on light touch/depression
sequences (similar to above).
[0277] Finally, similar to FIGS. 55/56, the sequences show a
similar "signature" an described where time is used again except
after a light touch first then a sets of sub-functions (in this
case three) where the sub-functions are selected by depressions
followed by a light touch.
[0278] Based on the above descriptions, it is apparent to one of
skill in the art that there are numerous sequences that can be used
to define different input sequences, none reliant on a
predetermined threshold for the primary detection of the touch. As
noted in any of the sequence figures related to time domain
differential processing rely on an absolute value for detecting at
feast the first touch. Of course, as shown above, even if one were
to use predetermined threshold in combination with the technique of
detecting dS/dt, reliability and new features can be added to
simple touch responses. Also, the sequences above could be used
with some success using predetennined threshold techniques by
carefully controlling the ranges with the conduction of the sensors
as described above (i.e., two touch points based on two threshold
values and in combination with time and number of sequences). The
limitations of predetermined threshold techniques as compared to
time domain differential processing techniques as described herein
would still apply.
[0279] As described earlier, time domain differential sensing
techniques for sensing touch inputs need to sample at a rate fast
enough to at minimum detect the rise and fall of ds/dt such as to
detect the touch. Even so the rate that a person can touch a touch
input sensing device is slow as compared to that of electrical
noise and other environmental conditions. Equally the rate of
change of touch stimulus change is much faster than other factors
such as temperature, moisture, ice, etc and certainly the static
offsets such as dielect.J.ic substrate thickness, dielcttic
constant, and other things that do not change at all (dS/dt=O) in
the environment. FIGS. 59/60 illustrate the application and use of
a filter 132 that can be employed electronically, software, or a
combination of both. The filter 132 may be constructed as a LOw
Pass filter such as to filler out changes that might affect the
stimulus at a rate That is greater than could be possibly be
performed by a human. Likewise the filter could also be used to
filter out slower signals in the form of a high pass filter. A
combination of a low pass and high pass filler or an integral fmm
of both to form a bandpass filter could be employed also. The
Stimulus and Detection circuit 134 would stimulate as necessary and
based on the techniques for sensing a touch stimulus and the sensor
electrode structure (whether a single electrode sensor or
multi-electrode sensor). The filter 132 would filter out those
frequencies that can't be related to a touch and then the Time
Domain Differential Processing circuit 114 would then identify by
the sequences S and dS/dt the "signatures" that relate to valid
output functions. Employing a separate filter would reduce the
signal processing speed requirements of the Time Domain
Differential Processing Circuitry 114. Also by divorcing the filter
function from the "signature" recognition function, the filter
block 132 can be tailored to tighter filter design at a lower cost
by using slate of the art integrated circuit designs. FIG. 59
illustrates the use of a single electrode structure and FIG. 60
illustrates how a filter 132 could be used in multiple sensor input
applications.
[0280] Refer to FIG. 61. FIG. 61 illustrates a dual electrode
structure for detecting a touch input, the dual electrode structure
having a first electrode 100 and a second electrode 104 positioned
proximate to the first electrode 100. A differential measuring
circuit can reject common mode signals, e.g., electrical noise,
interference, and temperature vatiations. The resultant
differential signals can be output processed using Time Domain
Differential techniques instead of using the Predetennined
Threshold techniques allowing the improved detection of touch
inputs as well as allowing tor the development of enhanced features
as described thus far. FIG. 61 indicates the use of an "inner" and
"outer" electrode 100, 104 each designated as Cinner and Couter.
Each electrode 100, 104 is stimulated, creating an electric field
as shown by the arrows stretching above and below each of Cinner
and Couter electrodes. The net electric field, based on the
differences in the Cinner and Cauter electric fields, is shown in
principle in FIG. 62. The electric fields in FIG. 61 can be
generated and measured, separated by time, to then be compared by
processing circuitry similar to that described previously in FIG.
26.
[0281] FIG. 63 shows Cinner and Cauter coupled to the Stimulus and
Detection Circuit 134 where each electrode's signal is filtered and
processed by the time domain differential signature processing
circuit 114. All of the blocks 110, 114, 132, 134 operate at least
as described in this disclosure. The Stimulus and Detection circuit
134 would first Stimulate and then measure the Cinner electrode by
turning on and then off control device 1. The Stimulus and Detect
Circuit 134 would then repeat this cycle but for Cauter using
control device 2. The difference of the resultant outputs of both
electrodes would then be output, along with other parameters
associated with the electrode that might be of use later by the
time domain differential processing circuit 114. Other possible
parameters might be each of Cinner and Cauter electrode's
non-differential signal value, the common mode voltage value, etc.
The output or outputs of the Stimulus and Detection Circuit 134
would then be coupled optionally to the Filter Function 132 which
in turn its output is coupled to the time Domain Differential
Signature Processing Circuit 114 where a touch event or sedes of
touch events, as defined by the sequence matching in the Time
Domain Differential Circuit block 114, as has been described
herein. The output of the Time Domain Differential Circuit 114 is
then coupled to the Output Response circuit 110.
[0282] Alternatively as shown in FIG. 64, each of Cinner and Cauter
would be stimulated and first and second Stimulus and Detection
Circuits 136, 138 would detect the electric fields on Cinner and
Cauter simultaneously. The electrical response for Cinner and
Cauter electrodes would be processed simultaneously by the Inner
Buffer 140. Outer Buffer 142, and Differential Buffer/Amplifier
144. The simultaneous processing of the Differential value of
Cinner and Cauter will greatly improve the common mode noise
immunity based on noise coupling in real time of the Cinner and
Canter values. The output of the Inner Buffer 140, Outer Buffer
142, and Differential Buffer/Amplifier 144 would be coupled to the
Filter Function 132 and the rest of the blocks to process similarly
as described previously and as shown in FIG. 64. Again, but with
greater effectiveness, differential measurement techniques result
in the suppression of electrical noise via radiated electromagnetic
interference or coupled through conducted electromagnetic
interference. In previous examples, the first step of processing
the stimulus S and dS/dt was detecting if the value of S had
exceeded a loose proximity setting of x to verify the signal was
strong enough to process the dS/dt event. The sequence for
recognizing the simple touch example from FIGS. 22, 23, 24 and 25
was as follows:
[0283] 1) If s>x (proximity threshold) [0284] and
[0285] 2) ds/dt>0, followed by
[0286] 3) ds/dt=0, then touch event
Using differential sensing techniques where the differential output
signal that is proportional to the touch but can attenuate the
electrical noise then the first step of the sequence can be
eliminated as follows:
[0287] 1) ds/dt>0, followed by
[0288] 2) ds/dt=0, then touch event
Where s=S(Cinner)-S(Couter) and ds/dt is based on the differential
output of Cinner and Cauter in FIG. 64.
[0289] This may be accomplished perhaps without the filter
function, depending on the patlicular application. The advantage of
eliminating the filter function would be a matter of possible
simplification and perhaps faster response times. Filter functions
lend to reduce response times. Also, by introducing differential
sensing techniques and even the filter function can reduce the
processing requirements of the Time Domain Differential processing.
In other cases it might be beneficial to implement the filler
function, in combination with differential sensing techniques,
using software digital filtering techniques.
[0290] Differential sensing techniques can also implement three
dimensional sensing techniques as discussed previously. In many
ways, many of the structures and layouts discussed earlier could be
used as the differential processing is largely implemented in the
electronic processing circuitry. FIGS. 65 through 68 illustrate
structures and layouts discussed previously that could be used with
differential electrode sensing with time domain differential
processing. FIGS. 65/66 are examples of three dimensional as
discussed previously but using differential sensing electrode
structures. The upper substrate of each electrode structure may be
flexible or dgid, consistent in operation to previous examples.
[0291] Shown in FIG. 69 is an electrode structure that will combine
the benefits of the sensing techniques described in FIGS. 35
through 40 and differential electrode sensing techniques. FIGS. 70
and 71 show comparable sensing techniques comparable to FIGS. 63
and 64. In particular, FIG. 69 illustrates the use of an additional
electrode 146. This additional electrode 146 is used as a strobe
electrode to couple a field to a sensing electrode 100 similar to
that described and associated with FIGS. 35 through 40. Unlike
FIGS. 35 through 40, FIG. 69 illustrates a strobe electrode 146
common to and for the purpose of coupling to two separate
electrodes, Cinner 100 and Cauter 104, simultaneously. The strobe
electrode 146 is located underneath Cinner 100 and Cauter 104 on
the opposite side of the substrate 148 that Cinner 100 and Couter
104 are located. The basic structure allows flor the additional
water immunity by coupling from a strobe electrode 146 to a sending
electrode, in this case two sensing electrodes simultaneously. FIG.
70 illustrates the strobe electrode coupled to Cinner 100 and
Cauter 104. The processing circuitry shows processing using
multiplexing measuring techniques. Similar to as described in FIG.
63, the differential sensing is calculated by measuring Cinner 100
and Cauter 104 separated by time. FIG. 71 illustrates a technique
similar that shown in FIG. 64 for measuring Cinner 100 and Cauter
104 differential sensing simultaneously, again with a common strobe
electrode 146 and a stimulus circuit 150. The combination of the
benefits of common mode rejection, water immunity, and time domain
differential sensing techniques as described previously can all be
integrated and utilized in by implementing the basic electrode
structure in FIG. 69 and in FIG. 71.
[0292] FIG. 72 shows the net electric field based on the difference
in electrical potential between Cinner 100 and Cauter 104 shown
coupled FIG. 69. FIGS. 73 and 74 show again as previously
described, structures associated with three dimensional electrodes
that can enhance the features that time domain differential sensing
can provide FIGS. 75 and 76 show an array of three electrode
structures as discussed relating to FIGS. 69 through 74. FIG. 75
shows the array of electrodes for Cinner and Couter and FIG. 76
shows the anay of electrodes for the Strobe electrode. FIGS. 77 and
78 are for an alternative example to that shown in FIGS. 73 and 76
relating to three electrode structures. FIG. 77 shows the an-ay of
electrodes for Cinner 100 and Couter 104 and FIG. 78 shows the
array of electrodes for the Strobe electrode 146. The electrode
structures depicted in FIGS. 77 and 78 are would be considered more
water immune than shown in FIGS. 75 and 76 based on the increased
coupling from the Strobe electrodes 146 to the Cinner 100 and
Couter 104 which helps distinguish from water versus human
touch.
[0293] Additional embodiments can include the differential sensing
techniques discussed above. For example, a capacitive sensor can
include a plurality of capacitive switches that are electrically
isolated from one another, where each capacitive switch includes an
electrode pairing having first and second electrodes. The
capacitive sensor can further include a differential measurement
circuit electrically coupled to each of the plurality of capacitive
switches, wherein the differential measurement circuit is adapted
to compare the self-capacitance of the first electrode against the
self-capacitance of the second electrode, either simultaneously or
sequentially, to aid in the detection of a stimulus proximate the
relevant capacitive switch. The differential measurement can also
be adapted to compare the rate of change of self-capacitance of the
first electrode against the rate of change of self-capacitance of
the second electrode. In this example, the rate of change of
electrode capacitance can be determined by a time domain
differential processing circuit 114 Substantially as discussed
above in connection with FIGS. 37-40. Further by example, the time
domain differential processing circuit 114 can be adapted to
determine the rate of change of a relative capacitance, where a
relative capacitance includes the difference between the first
electrode self-capacitance and the second electrode
self-capacitance. Still further by example, the time domain
differential processing circuit 114 can be adapted to measure the
rate of change of a mutual capacitance between the first and second
electrodes A related method can include a) providing a plurality of
electrode pairings, each including an inner electrode and an outer
electrode, b) measuring the self-capacitance of each electrode in
the plurality of electrode pairings, and c) comparing the
self-capacitance of each inner electrode against the paired outer
electrode to determine the presence of a stimulus proximate that
electrode pairing, optionally using a single differential sensing
circuit. The method can further include comparing the rale of
change of capacitance of the inner electrode with the tale of
change of capacitance of the outer electrode for each electrode
pairing. The method can still further include comparing the
capacitance of the inner electrode against the capacitance of the
outer electrode to define a relative capacitance, and determining a
change in relative capacitance over time.
[0294] Another embodiment includes a touch pad or touch screen
including electrode rows and electrode columns electrically coupled
to a differential measurement circuit. In this embodiment, the
differential measurement circuit is adapted to compare the
self-capacitance of the one or more electrode rows against the
self-capacitance of one or more electrode columns, either
simultaneously or sequentially, to determine the presence or
absence of a stimulus on the touch screen display. The differential
measurement can also be adapted to compare the rate of change of
self-capacitance of an electrode row against the rate of change of
self-capacitance of another electrode row. In this example, the
rale of change of electrode capacitance can be determined by a time
domain differential processing circuit 114 substantially as
discussed above in connection with FIGS. 37-40. Further by example,
the time domain differential processing circuit 114 can be adapted
to determine the rate of change of a relative capacitance, where a
relative capacitance includes the difference between the
self-capacitance of one row or column with the self-capacitance of
another row or column. Still further by example, the time domain
differential processing circuit 114 can be adapted to measure the
rate of change of a mutual capacitance between two rows, two
columns, or one row and one column. A related method can include a)
providing plurality of electrodes including electrode rows and
electrode columns, b) measuring the self-capacitance of each
electrode row and each electrode column, and c) comparing the
self-capacitance of at least two of the plurality of electrodes to
determine the two-dimensional location of a touch input on the
touch screen display, optionally using a single differential
sensing circuit. The method can further include comparing the rate
of change of capacitance of a row electrode with the rate of change
of capacitance of another row electrode of a column electrode. The
method can still further include comparing the capacitance of any
two electrodes to define a relative capacitance, and determining a
change in relative capacitance over time.
III. Matrix Electrode Touch Sensors
[0295] FIGS. 79 through 85 illustrate a series of columns of
electrodes 152 and rows of electrodes 154 that can be arranged to
fonn a matrix 156 for detecting multiple points using time domain
differential techniques as discussed previously. The matrix of
electrodes 152, 154 may be opaque, translucent, or transparent and
may be made of conductors, semiconductor, or resistive materials
using screen printing, electro-less, electroplating, or other
techniques including embedding or assembling wires or other
subassembly components on or into a carrier substrate. A
construction of the matrix 156 can include a dielectric 158
interposed between the electrode columns 152 and the electrode rows
154. For example the matrix 156 can include a conductive material
such as printed silver epoxy on polyester or polycarbonate film or
glass, copper on glass or printed circuit board, indium tin oxide
(ITO) on polyester or polycarbonate film or glass, or carbon nano
material deposited on firms or glass. FIGS. 79 and 80 are side
illustrations of how electric fields may be generated from the
columns and rows by any of the techniques used to detect
capacitance change including that which is described herein. The
columns shown in the side view in FIGS. 79 and 80 are shown in a
top view in FIG. 81 and likewise the rows shown in the side view in
FIGS. 79 and 80 are shown in a top view in FIG. 82. FIG. 83 shows a
combined view of the columns and rows in a top view.
[0296] FIG. 84 illustntes a basic sensing circuit 170 employing
concepts as described earlier in FIGS. 59 and 60 but applied to the
column/row matrix in FIGS. 79 through 85. This circuit 170 would
sample each column 152 and then each row 154 then, using time
domain differential sensing using the parameters as described
previously, determine the appropriate touch signature for the
desired output response. FIG. 85 illustrates a column that is
driven and read using the circuit sampling technique in FIG. 84. As
each column electrode is stimulated, electric fields similar to
that shown in FIG. 79 will be generated. Similarly, FIG. 86
illustrates a row that is driven and read using the circuit
sampling technique in FIG. 84. As each row electrode is stimulated,
electric fields similar to that shown in FIG. 80 will be generated
Differential electrode sensing time domain differential sensing
techniques may be used also, as described relating to FIGS. 60
through 63. FIGS. 88 through 90 illustrate how a "virtual" inner
and outer electJ. ode structure may be made by analyzing three
column electrodes and three row electrodes. FIG. 88 illustrates the
sensing of three columns of electrodes, each individually, using
the Circuit shown in FIG. 84. FIG. 89 illustrates the sensing of
three rows of electrodes, each individually, using the circuit
shown in FIG. 84. The integrating of the outer most columns and
outer most rows of electrodes, a virtual outer electrode is
created. The integrating of the inner most column electrode and
inner most row electrode and virtual inner electrode is created.
The difference of the virtual inner and virtual outer electrode
creates the basic attributes of the differential electrode
structure in show in FIGS. 61 and 62. The location is known the
virtual electrode in the matrix by know the address of the
electrodes for the columns and rows when taking the measurements.
This is illustrated in the shaded area at the intersection of the
column electrodes and row electrodes in FIG. 90.
[0297] FIGS. 91 and 92 illustrate a flow chart that is similar in
operation to that described in FIG. 20. The additional criteria of
interpolating the location of an input located between the
electrode columns and rows after a touch signature is detected. The
flow chart in FIGS. 91 and 92 show the signature of a basic touch
input. The interpolation of a touch location is not performed until
after a touch signature is recognized. Similar to conventional
capacitance sensors for single buttons that use a predetermined
threshold value to determine a touch and with the resultant
deficiencies described earlier, projected capacitance touch screens
that use predetermined threshold values to determine a touch also
have similar issues. By using time domain differential techniques
as described herein the benefits of single input touch electrodes
can be used to improve the performance of touch screens, mouse
pads, and other high resolution/high input devices. The matrix
touch input device shown in FIG. 90 would have at least 209 single
inputs. The matrix with interpolation would approach the same
resolution as that of a typical capacitance touch screen but with
the added benefit of accurate touch input with a bare finger
without a glove on or a finger with a glove on as well as the other
features such as unique signature definition for touch that would
then nigger the interpolation of the location. The flow chart in
FIGS. 91 and 92 can be modified in a variety of ways. For instance
all of the data for all of the electrodes could be sampled and
stored and then analyzed for touch signature and if there is a
valid touch signature match then interpolation and gesture
recognition. FIGS. 91 and 92 illustrate the sample of one electrode
at a time for a valid touch input and in the event there is then
interpolation and gesture recognition is deciphered. FIGS. 93 and
94 illustrate the concept of looking for a match of a touch
signature match as well as a match for a non-touch signature. This
concept illustrates that in some case the very touch signature
using the parameters and techniques described herein that time
domain differential sensing techniques may be considered
fundamental in gesturing at the touch deciphering level.
[0298] FIG. 95 illustrates a modified version of the circuit shown
in FIG. 84 for simultaneously stimulating three electrodes at a
time for columns and rows. For instance, switches 13B and 15B would
be selected to route Columns 2 and 4 to the Stimulus and Detection
Circuit for Outer circuit block 138 and 14A would be selected to
route Column 3 to the Stimulus and Detection Circuit for Inner
circuit block 136. The absolute value and the differential signal
would be processed and sent to the Filter Block 132 and the Time
Domain Differential Signature Processing Circuit 114. The benefits
of simultaneously measuring the electrodes would be beneficial in
like manner as described previously as associated with FIG. 64.
Likewise and similarly, Rows 3, 4, and 5 can be measured by
selecting switches 3B, 5B, and 4A to Rows 3, 4, and 5 respectively.
Again, the addressing of the columns and rows will determine
virtual touch zone for the matrix sensor 170.
[0299] FIGS. 96 and 97 illustrates side views of a matrix touch
sensor 170, similar to that described in FIGS. 35 through 40.
except as applied in a column and row matrix. FIG. 96 illustrates
coupling from the Row electrode 154 to the Column electrode 152 by
strobing the tow electrode 154 and then looking for responses on
the columns 152. Conversely, FIG. 97 illustrates coupling from the
Column electrode 152 to the Row electrodes 154 by strobing the
Column electrode 152 and then looking for a response on the Row
electrodes 154. FIG. 98 is a circuit for stimulating a column and
then reading the responses on a row R1. One could strobe only
columns and read rows or only strobe rows and read columns but to
increase robustness doing both can increase the robustness. FIG. 99
illustrates the circuit in FIG. 98 with the added provisions of a
stimulus selection circuit 160, 162 for routing the stimulus to any
of the rows or columns, individually. Likewise, FIG. 99 illustrates
the basic circuit in FIG. 98 with the added provision of a
selection circuit for routing the response from any of the rows or
columns to the response detection circuit 164. The flow charts
shown in FIGS. 91 through 94 would be applied as described above to
determine if there is an initiating touch signature event,
interpolation, and gesture recognition, and the column/row and/or
row/column selection can determine the location of the touch in the
matrix.
[0300] FIG. 100 illustrates the individual selection of a row for
strobing and the reading of two columns. All columns could be read
simultaneously with one strobe but a more cost efficient method
would be to strobe the same row while then measuring an
individually selected column. The process would repeat until all of
the columns and their responses are measured, albeit at the expense
of processing time. Note that one row stimulus can be used to
detect two separate touch responses along separate columns. FIG.
101 illustrates conversely the strobing of a column while
individually selecting and reading the responses of rows. Note
again that there can be two responses from two different rows with
the stimulus of one strobing one column. FIG. 102 illustrates the
common intersection of a touch input that would be common to both
strobing rows and reading column responses and the strobing of
columns and the reading of row responses in FIGS. 100 and 101. Also
in this technique of sampling, each column/row and/or row/column
combination is individually sampled. Even though sampling in done
selecting individually, the techniques of differential sensing may
be used similar to that desclibed earlier.
[0301] An additional differential sensing technique may be
implemented as described in FIGS. 103 through 109. The basic
strobe/sense technique as described in FIGS. 96 through 102 are
used with the exception that instead of reading the responses from
selected individual columns 152 and/or rows 154, groups of three
selected columns and/or rows are made simultaneously and then
processed per FIGS. 105 and 106. FIG. 105 illustrates a technique
as related to FIGS. 36 and 37 and FIGS. 69 through 71. When
selecting any three columns or any three rows for responses, the
outermost columns or outermost rows are selected simultaneously and
routed to the Outer Detection Circuit 138 where the output is sent
to the Outer Buffer 142 and Differential Buffer/Amplifier 144 for
processing later by the Time Domain Differential Processing
Circuitry 144. In addition, the innermost row or innermost column
is selected and routed to the Inner Detection Circuit 137 where the
output is sent to the Inner Buffer 140 and Differential
Buffer/Amplifier 144 for processing later by the Time Domain
Differential Processing Circuitry 144.
[0302] FIGS. 107 through 109 are similar to FIGS. 100 through 102
in that there is a strobing of columns and reading of responses
from rows and conversely the strobing or rows and reading of
responses of columns, with the exception that instead of selecting
individual rows and columns for reading responses there is the
selecting of three rows and columns simultaneously. Note again, in
FIG. 107 that there can be two or more responses on rows for a
column strobe and similarly in FIG. 108 there can be two or more
responses on columns for a row strobe. FIG. 109 illustrates the
common intersection of a touch input that would be common to both
strobing of columns and reading tow responses and strobing of rows
and reading columns responses in FIGS. 107 and 108. Again, the flow
charts in FIGS. 91 through 94 would be used and the techniques and
benefits described for differential electrodes using time domain
differential signature recognition processing would apply.
[0303] FIGS. 110 through 129 illustrate other potential uses of
time domain differential touch signature processing using three
dimensional touch sensors. FIGS. 110 through 113 illustrate the
addition of a flexible substrate 122 to any of the basic structures
shown in FIGS. 81 through 83, 85 through 87, 88 through 90, 100
through 102, and 107 through 109. The flexible substrate 122 would
be used similarly as the techniques used to describe FIGS. 41
through 43, 65, 73, 74. FIG. 110 and FIG. 112 illustrate side views
of electric fields formed by the columns and rows when they are
stimulated as shown in FIGS. 81 through 83 and FIGS. 85 through 90.
FIG. 111 and FIG. 113 illustrate side views of electric fields
formed by the columns and rows when they are stimulated as shown in
FIGS. 100 through 102 and 107 through 109. FIG. 114 illustrates how
a stylus 172 may be used and FIG. 115 illustrates the use of a
finger 174. If the stylus tip is connected to a conductive
material, and if this conductive material is coupled to the hand of
the human, then a stylus can be used in the structure similar to
the finger shown in FIG. 115. The added benefit of a smaller more
highly resolute input stimulus might be used. FIGS. 116 through 119
illustrate another variation of a three dimensional electrode
structure using the column/row matrix construction. A three
dimensional electrode structure can include a gap, optionally an
air gap, between the electrode rows and the electrode columns. A
three dimensional electrode structure can also apply to
conventional capacitive sensing and differential sensing, in
addition to time domain differential sensing. This variation allows
for the flexing of the column/row matrix towards a biased electrode
(such as ground) 128 to affect the change of stimulus as the finger
174 or stylus 172 moves die column/row matrix towards the biased
electrode 128. The biased electrode 128 can include any DC
potential, pulsed AC potential or strobed, and can be positioned
adjacent the upper substrate 122. Other configurations are also
possible, provided there is relative movement between a sensing
electrode and a biased electrode. The finger or stylus will cause
an increase of stimulus as either approach the touch Substrate 122
surface 112. An increasing stimulus will be inserted as the stylus
or finger move die flexible column/row matrix (localized) towards
the biased electrode 128. FIGS. 120 and 121 illustrate the use of a
finger 174 and stylus 172.
[0304] FIGS. 122 through 129 illustrate the use of a three
dimensional time domain differential electrode structure made of
two rigid materials 102 and 122 separated by spacers 124 that are
compressible. FIGS. 122 and 124 show side views of lop rigid sensor
assembly constructed of a rigid substrate 122. The construction
shown also would apply specifically to a matrix type touch input
device 170. The top rigid sensor substrate 122 would be directly or
indirectly supported by a spacer material 124 that can be
compressed to allow the two rigid substrates 102 and 122 to move
closer together without much deflection of the upper rigid
substrate 122 when pressed by a finger 174 or stylus 172. When a
stylus 172 or finger 174 move towards and touches the rigid upper
sensor substrate 112, the time domain differential touch signature
techniques would be used to determine the match of a touch input,
then interpolation and gesture recognition. If the stylus 172 and
finger 174 were to exert pressure after the touch condition such as
to cause the spacers 124 that are supporting the rigid upper sensor
assembly to compress allowing the sensor electrodes 152, 154 to
move towards the biased electrode 128, then using time domain
differential processing techniques will allow additional features
to be added based on a third dimensional input. These added
features are similar to that which was desctibed in FIGS. 46, 47,
48, 50, and 66. FIGS. 126 and 128 illustrate the use of stylus and
finger for detecting the touch condition without compressing the
spacers 124. FIGS. 127 and 129 show movement and decreasing of
space between the two rigid substrates 122 and 102 (increasing the
stimulus because of the biased electrode) by moving the rigid upper
touch surface 122 towards the lower rigid substrate 102.
[0305] Additionally by sharing the conductive rows and columns and
the lower conductive biased electrode with a haptics driver, the
same construction may be used for generating the third dimension of
touch sensing and may also be used to generate haptics response.
Haptics feedback is becoming more and more popular as the user
expetience is enhanced when a touch input is made by causing a
tunable vibrating stimulus at the finger indicating that a touch
was interpreted by the user device as well as providing a different
vibrating response depending on the type of touch signature or
touch signature/gesture is provided. Time domain differential is
particularly useful with haptics as the actual moment of touch is
determined which in turn can be used to generate haptics feedback.
This would be in contrast with systems that u se predetermined
threshold techniques where a touch input may be falsely or
prematurely be interpreted causing the haptics response to bigger
to soon or sluggishly. The advantage of using time domain
differential sensing as described herein will be true in any
haptics application. The integrated haptics/time domain
differential signature electrode structure shown in FIGS. 122
through 129 (when the electrodes on the upper and lower rigid
substrates are shared) can provide tor a reduced package profile in
mobile and other devices. For example, a capacitive sensor can
include an upper substrate 122 for receipt of a touch input
thereon, an upper electrode 152 supported by the upper substrate
122. slower electrode 154 spaced apart from the upper electrode
152, and a lower substrate 122' for supporting the lower electrode
152. An integrated circuit, micro-controller, or FGPA for example
can include both a processing unit to detect a touch input and a
haptics driver to induce an electrostatic force between the first
and second spaced apart electrodes 152, 154 to vibrate the upper
substrate 112 in response to a touch input thereon. By combining
the processing unit and the haptics driver into a single integrated
circuit, for example, the haptic response latency is potentially
reduced. In addition, the processing unit can include a time domain
differential sensing circuit and/or a differential sensing circuit
as substantially set forth above. The vibration of the upper
substrate 112 can be performed by dedicated haptics controller in
other embodiments, however. In these and other embodiments, control
of the haptics driver and touch sensing can be interleaved. Further
optionally, the upper electrode 152 can include a plurality of
electrode rows, and the lower electrode can include a plurality of
electrode columns as substantially set forth above in connection
with FIGS. 81-82.
IV. Time Domain Differential Sensing in Light Sensors
[0306] Time domain differential sensing techniques can be applied
to the sensing of other parameters such as light. FIG. 130
illustrates the use of LED lighting and light sensors 200 to
determine the signature of an object above a surface 202. FIG. 130
illustrates a single row array of sensor pads 204 with LED
apertures A1 and A2 to allow for the projection of light emitted by
LEDs L1 and L2 located underneath the apertures. There are two LEDs
and apertures, one LED and aperture at one end of the sensor strip
and another LED and aperture at the opposite end. There is one
sensor, S1, located in the middle of the strip for sensing the
reflected light objects, as they move toward the touch surface,
from the LEOs L1 and L2. The aperture size and geometry would be
sized such that the intensity of the light would vary as an object
is moved over top of the sensor strip. As an object moves from the
left to the right, the intensity of the light would vary roughly
proportional to the sin(h2) and sin(h1). Angle h2 would decrease as
an object moves from the left to the right and the light from
aperture A1 is reflected by the object to sensor SI and would
decrease in intensity in proportion the angle h2. Simultaneously,
the light, emitted from aperture A2 and reflected by the object to
sensor S1 would vary in intensity roughly proportionate to the
sin(h1). LEDs L1 and L2 would alternate in stimulation by a drive
circuit. In other words, L1 would be turned on and Sensor S1 would
measure the intensity of the reflected light and process or store
for later processing. L1 would be turned off and L2 would be turned
on and the reflected light intensity reflected off the object would
be measured by S1 and processed or stored later for processing. The
intensity of the light reflected from LEOS L1 and L2 would both
decrease simultaneously if the object were to remain fixed above
the sensor strip but move perpendicular towards the surface.
Conversely the reflected intensity would increase in the reflected
light off an object if that object were to remain fixed above the
senior strip yet move away from the sensor strip surface. Instead
of measuring the change in stimulus of an electric field but
measuring this stimulus change in light intensity, an object would
be able to be tracked up, down, left, and light above the sensor
strip 200 adding a third dimension above the touch sensor pads 204.
As a finger or stylus moves above the surface 202, different
finger/hand signatures can be captured to supplement the
interactivity of the touch signature at the touch surface 202 as
described herein previously.
[0307] The concept of using light in conjunction with rows and
columns of touch electrodes can be implemented as discrete buttons
or high resolution touch matrices. FIG. 131 illustrates one
possibility for extending the time domain differential sensing on
an XY matrix application such as a mouse pad or touch screen 210.
FIG. 132 shows variables as they relate simple analytical
trigonometry to determine location in three dimensional space above
a plane (which would be the touch screen, touch pad, or keyboard).
The touch pad or touch screen can include integrated haptics
substantially as set forth above in connection with FIGS. 122
through 129. The formulas apply in general in which the light
intensity would vary proportionally to following:
x=r*sin(angle r)*cos(angle y)
y=r*sin(angle r)*sin(angle y)
z=r*cos(angle r)
r= {square root over (x.sup.2+y.sup.2+z.sup.2)}
Angle y=inv tan(x/y)
Angle r=inv cos (z/ {square root over
(x.sup.2+y.sup.2+z.sup.2)})
Where the intensity from the light apertures would vary with angle
(r).
[0308] As the term is used herein, a "capacitive sensing circuit"
is any circuit including one or more electrodes having a
capacitance that varies in response to the presence of an object,
for example a finger, a glove or a stylus. Capacitive sensing
circuits can include, for example, a single electrode, an electrode
pairing, multiple electrode pairings, a sample and hold capacitor,
multiple sample and hold capacitors, an electrode row, multiple
electrode rows, an electrode column, multiple electrode columns, a
multiplexor, and combinations thereof, whether now known or
hereinafter developed. As the term is used herein, a "capacitive
sensor" includes a capacitive sensing circuit (e.g., at least a
single electrode) in combination with one or more processing units
to provide a output inductive of a stimulus. Exemplary processing
units can include an analog filter, an analog to digital converter,
a digital filter, a differential processing unit, a time domain
differential processing unit, a time domain differential signature
processing unit, a stimulus detection unit, a gesture recognition
unit, a haptics driver, and combinations thereof as optionally set
forth in connection with FIGS. 16-129. The processing unit(s) can
be analog or digital, and can include for example one or more
integrated circuits, micro-controllers, and FPGAs for example. The
capacitive sensors of the present invention can be used across of
range of applications where the detection of a stimulus is desired,
including touch sensors, touch screens, touch panels, and other
control interfaces whether now known or hereinafter developed.
[0309] The above description is that of current embodiments.
Various alterations and changes can be made without departing from
the spirit and broader aspects of the invention as defined in the
appended claims, which are to be interpreted in accordance with the
principles of patent law including the doctrine of equivalents.
This disclosure is presented for illustrative purposes and should
not be interpreted as an exhaustive description of all embodiments
of the invention or to limit the scope of the claims to the
specific elements illustrated or described in connection with these
embodiments. For example, and without limitation, any individual
element(s) of the described invention may be replaced by
alternative elements that provide substantially similar
functionality or otherwise provide adequate operation. This
includes, for example, presently known alternative elements, such
as those that might be cun-ently known to one skilled in the art,
and alternative elements that may be developed in the future, such
as those that one skilled in the art might, upon development,
recognize as an alternative. Further, the disclosed embodiments
include a plurality of features that are described in concert and
that might cooperatively provide a collection of benefits. The
present invention is not limited to only those embodiments that
include all of these features or that provide all of the stated
benefits, except to the extent otherwise expressly set forth in the
issued claims. Any reference to claim elements in the singular, for
example, using the articles "a," "an," "the" or "said," is not to
be construed as limiting the clement to the singular. Any reference
to claim elements as "at least one of X, Y and Z" is meant to
include any one of X. Y or Z individually, and any combination of
X, Y and Z, for example, X, Y, Z, X, Y; X, Z; and Y, Z.
* * * * *