Apple Inc. v. Samsung Electronics Co. Ltd. et al

Filing 561

Declaration in Support of #559 Declaration in Support, filed byApple Inc.. (Attachments: #1 Exhibit 3.02, #2 Exhibit 3.03, #3 Exhibit 3.04, #4 Exhibit 3.05, #5 Exhibit 3.06, #6 Exhibit 3.07, #7 Exhibit 3.08, #8 Exhibit 3.09, #9 Exhibit 3.10, #10 Exhibit 3.11, #11 Exhibit 3.12, #12 Exhibit 3.13, #13 Exhibit 3.14, #14 Exhibit 3.15, #15 Exhibit 3.16, #16 Exhibit 3,17, #17 Exhibit 3.18, #18 Exhibit 3.19, #19 Exhibit 3.20, #20 Exhibit 3.21, #21 Exhibit 3.22, #22 Exhibit 3.23, #23 Exhibit 3.24)(Related document(s) #559 ) (Jacobs, Michael) (Filed on 12/29/2011)

EXHIBIT 3.15

.

initiated

by

a

touch

on the surface.

oetween the arrival ož the echo and
transmission

of

the

the

The time intervals
beginning

of

the

source signal, measured in two direc-

tions as shown Fig. 2.3 give the information on the position
of

the

object.

The touch sensor shown Fig. 2.3, developed

by T.S.D Limited (ref 2.4], actually provides outputs of x+y

and 2y enabling the derivation of x and y where x and y are
the distance horizontally from .a vertical

edge

and

verti-

cally from a horizontal edge respectively.

Video Technique:
The video approach to the touch input device uses a T.V
camera

to

is placed.

scan a translucent plate on which the finger tip
The signal from the TV camera is then

processed

to obtain one bit of information per pixel.

Using a pro-

grammable threshold voltage, one bit per pixel

is

to determine
the plate.

obtained

the shape of a 2-D projection of an object on

The data resulting from this process are

stored

in a memory to which access by a dedicated processor is
allowed. This processor implements further processes such as

determining non-zero locations in the memory (that is, the
position of the object) and identifying shapes (groupíng the
pixels for an object).

Nimish Metha presented such a system

[ref 2.5) whose basic configuration is shown in Fig.

2.4.

Capacitive:

2-5

APLNDC00026340

CURVED GLASS SCREEN
ACTivE AREA

PIEZOELECTRIC TRANSDucERS
RECEtVER

--

- -3

CONTROL LINES
PARALLEL OUTPUT

X-Y POSITIONS
PARALLEL OUTPUT)
TIMING

OtGITAL
CONTROLLER

ECHO OUTI

SERIAL OUTPUT

I

\·

\

\

POWER

L..-OP1tONAL
TIMING

PtEZOELECTRIC
TRANSDUCERS

TRANSMITTER

Fig. 2.) Block Diagram of Touch Screen Digitizer

APLNDC00026341

att Eitt AT

t(i Y

sirit 11 .

'KL YtinAhll'
AkiA

I

\.

\ \
\ \

/

I

/
/

/

/

TV CAMENA

un iPUT
lit.V itt

il Ni i

COMPUTER

Fig. 2,4

Video System for Touch Tablet

APLNDC00026342

Capacitive sensors are
such

as

used

in

various

single touch switches and touch tablets. Two kinds

of touch tablet using capacitive sensors
here.

applications

The

be

examined

one developed by TASA (ref 2.6) shown in Fig 2.5

measures the capacitance between
covered

will

by

the

plate

and

the

area

the touch. This measured datum is then compared

with a previous reading stored in a shift register. In order
to reduce the

size of

the shift

register, a tablet is

divided into many sub-regions in which the position
touch

is

uniquely

located.

the .

One· such sub-region is much

larger than the maximum size of a
avoid

of

single

touch

so

as

to

an overflow. TASA utilizes the sensor to detect rela-

tive movements of a.finger rather than

its

absolute

posi-

tion.
Another capacitance tablet developed by Sasaki,

kow

and

others at the University of Toronto (ref 2.8] uses

sensors for the rows and columns which
shown

in

Fedor-

Fig 2.6.

are

interleaved

as

It uses analog multiplexors to select a

row or a column sensor.

In order to find the capacitance of

a row or a column, it counts the time to charge up the capa-

citive sensor.
the

Because the capacitance of

the

sensors

on

tablet without a touch is not constant, and the capaci-

tance change produced by a touch is
pared

to

the

capacitance

relatively small

com-

of the surroundings, the system

uses a neasure of the initial capacitances of the sensors
without

touch

)

(

whose values are stored in the memory.for

2-6

APLNDC00026343

The couch point is determined by finding
ereancemaximum difference

a

sec

values (current value less the

reference value) for the rows and columns.

2.3 SHORTCOMINGS OF EKISTING DEVICES

The scanning properties of the devices described in the
previous

section

can

be

distinguished depending on their

position, pressure and multiple touch sensing
All

the

devices

or

capabilities.

transducers referenced are capable of

locating the position of a touch, with a resolution which is
characteristic of each device.

Only capacitive sensors and

the MIT resistive sensor provide pressure of

touch whereas

the video system and the MIT tesistive sensor give a multiple touch capability.

Projective sensors, that is, all of the sensors
duced

intro-

in the previous section except the video system and

the HIT high resolution resistive sensor, cannot detect multiple touches without ambiguity since the detection of touchby two horizontal and two vertical

sensors

can be

inter-

preted in seven possible ways as shown in Fig, 2.7.
In general, the missing data may be retrieved by intro-

ducing more axes, as is done in a tomographic imaging system.

Using this scheme, if the upper limit of the number of

touch points is

tWor

the

introduction of one more axis

2-7

APLNDC00026344

.L

herial In Shift
2egister (Previous)
Pattern Comparison Motion

Detection
Parallel Load Shift Register
(Present)
Etc

Etc
Touch Surface Sensor

Touch Jensitive Circuitry

Down Count
Up Count

Finger not Moving

Finger Moving U

Finger Loving Down
Fig. 2.5

Block and Time Diagram of TASA Touch Tablet

APLNDC00026345

I

SENSORS

COLUMN SEliSORS

Fig. 2.6 Capacitive Sensor Configuration
of the U of T Touch Tablet

5

APLNDC00026346

ciearly òistinguishes at least two points as shown
in

to

the

number

to

an

of touches is not assumed.

which the number of touches is more than two
(c)

anò

Fig 2,7. .At least two additional axes are required

istinguish two points without ambiguity if
limit

(a)

(g) in Fig. 2,7,

are

upper

Cases in
shown

in

But as soon as the number of axes

is increased, the attraction of any scheme of 2-d projection
diminishes .because the cost of implementation rises greatly.
For example the.capacitive tablet may

mentable

an

unimple-

number of wire layers whereas introduction.of sen-

sors and sources
extremely

require

for

diffidult.

IR

and

Moreover

Ultrasound

schemes

may

be

as the number of the touch

points increase, additional axes do not help in resolving
.

basic

shortcoming

a

of the sensor from which only on and off

information is available.

This is the existence..of a region

for which identification of points inside is not possible as
shown Fig. 2.8.

The video technique

seems to solve

all

the

problems

embedded in all of the "projective sensor" systems.including.
pressure if
corresponds

"area of -touch" by a
to

the

pressure.

compressible finger

But a video system is quite

bulky due to the optical enclosure and it is slow because it

has

to

access the data stored in memory by the camera pro-

cessing unit. The maximum speed is limited by the scan

rate

of the camera(30 per second) even though this maximum can be
achieved only by pipelining all the processes required.

2-8

APLNDC00026347

(¿.)

Éetection of touch by row
sensors (c), (b) :.nd colue:n
sensors (c), (d) can be
.interpreted in 7 possible a ye

(b)

r.s shown below.
I

(c)

(d)

A

e

C

D

I

E

F

ig. 2.7 i ossible sets of points whose e::istenev :.: y 40
implied by two sensors on both row r na coluran.

APLNDC00026348

Fig. 2.8 Concave touch points that block the points inside.
Any point or g,roup of points within the shaded
region cannot be identified by any number of
projections.

APLNDC00026349

AGES TO THE PROBLENS

Dae concludes from the previous discussion that
ing

systens and devices òo not provide an appropriate means

to reach our goal.
sor

exist-

is

The major problem of the projective sen-

generally

the ambiguity on multiple points,

As a

solution to this problemt multiple axes are required.
however,

This

increases the cost as well .as the number of points

to be scanned.

guity within

Furthermore it cannot

regions of

reasonable number of axis.

eliminate

the

ambi-

"concave touch points" using any
On this basis,

all

projective

methods must be discarded.
One idea of some significance that can be introduced is
to avoid scanning all the pixels in the tablet which contain

no information.

For example, scanning all 2048 points of

a

tablet having a resolution 64 by 32 for fewer than 10 points
is really quite a ridiculous

number of

approach.

In

fact,

if

the

the points to be searched is comparably small,

then an improved algorithm, here called binary scanning, can
be used. .It is described as follows.
Consider a plane of a tablet with resolution 8 by 8
be searched

for

a

to

touch point as shown in the Fig. 2.9.

First, check the tablet for touch as a whole region as shown
by the area ABCD in the figure. If touch is detected, divide

the tablet into two equal regions shown by the line

EF

and

check each of the two regions ABEF anã EFCD žor toucheòness.

2-9

APLNDC00026350

region, region EFCD
c:t ©

in

this

case,

and

coucha two equal regions as shown by the divisi.on

enis into
Continue this PEO~
aavido
the touched regio •
Isac Ug, select arther division is Possible, that is, until a
cess until

designated as the region PKNO in gig.

2.9,

16

"gg sensorThe figure also shows the sequence of suodivisi
reached•
eration. Rote details Of.this algo
in the binary scanning CP
githm are given in chapter 4.
Using this algor

tablet

e aon

6a4 bhy- 3

r gneires tntentyn

a

having

scanning times:
2*1092(64*32)=22

el
dn

p

e1 s a

9

Une

o

Bethe time that it would take to detect one

touch

if

all pixels are scanned one by one linearly is

64*32
N=-----=186.
22

This shows immediately that the binar he nanm eDr Ofmethond

is

much a Pacior to linear scanning
be scanned is fewer than 186.

2-10

APLNDC00026351

s

s

(1)

N

t

‡x

L

c

(2)

Fig. 2.9 Binary scanning operation.
(n)-Sequence of subdivision in binary operation.

APLNDC00026352

-ror example the speed gain.over
cae nu

linear

scanning

when

i of points is ten is

64*32
-----=9.3

22*10

That is, for 10 points binary scanning is
-

about

9,3

times

faster than linear scanning.

Now compare such a 64*32 binary scanning tablet with a
2-d projective touch tablet such as used in the HP Personal
Computer Input Screen, or with the capacitive

single

touch

tablet with 64 by 32 resolution. In each case the speed gain
for detection of a single touch is -

64+32
22

-4.36

or a'oout 4.3. That is, the binary scanning tablet is
tially

4.3

poten-

times žaster than one žor which only sequential

scan is possible.
Even if the binary scanning algorithm is applied to the
projective

tablet, the speed for the projective tablet will

not exceed the speed of the 2-d image tablet.

The

scanning

time for a projective tablet having the same resolution is
found as follows; Since there are 64 + 32 sensors only,

and

the binary scanning algorithm is.applied to the row and the
colu¤n sensors separately, the scanning time is

2-11

APLNDC00026353

-

;•1oß2(64)+2*lo92(32)=22

Thus the binary scanning algorithm seems to be
attractive

one

tot

application to the FHTSID.

a

very

However it

necessitates two special hardware features:

--

1. Unlike the projective sensor system which allows to

address only a group of positions in a column or a row,
all individual positions of m by

n

tablet

should

be

addressable.

-- 2. It should be able to group

a

numbet

of

adjacent

The first requirement is to permit sensing of

multiple

sensors as one larger sensor region.

touches,

cithm.
of the

the

second

allows

for the binary scanning algo-

In addition to these necessary features,
intensity

a measure

of touch should be considered as a third

requirement to increase the capability of the FMTSID.
The sensors

that can possibly

accommodate , these

requirements are many. However the degree of dižficulty in
implementation varies one to
various

sensor

types

another.

In

the

following,

are examined in view of the require-

ments identified above.
A resistive image sensor can
modification

of

the

be

used

with

a

slight

multiplexor as shown in the Fig. 2.1,

2-12

APLNDC00026354

. .

novever far too much time-is required to evaluate the resistance

using

two port parameter calculations.

Besides, the

basic approach requires that all the row resistances have to
be

evaluated

once

using

linear scanning; that is, binary

scanning is not applicable to rowwise scanning. .
For the video system, the row and the

registers

column

scanning

are not accessible and with the video data stored

in memory, it is not possible to satisfy the second requirement,

Bowever the third requirement may be met by the addi-

tion of a little more hardware.

In general,

therefore,

it

is not a good choice.
None of the other devices presented
section

satisfy

in

the

previous .

the requirements.. Thus it is necessary to

identify further sensor types.
A resistive polymer (J.S,R) was examined (ref 2.7]. The
polymer

changes

resistivity with applied pressure. One of

the applications shown by J.S.R has two closely-placed,
separated,

metal coated plates on the PC board on which the

rubber sheet lies such .that if the rubber is
the

but

two plates are connected.

pressed

down,

This unit may 'oe used with a

lot of multiplexors to select one

of

all

sensors

on

the

board. However a problem with this sensor is that it takes a
very long time žor the material to recover
the

original

electrically

to

state after the žinger is released (about 100

maec).

2-13

APLNDC00026355

Piezoelectric material was also examined. One
approach

is

to

apply

the same hardware technique used in

keyboard applications.
inate

the

possible

However this approach does not elim-

multiplexing

problem.

Unfortunately during the

time required for multiplexing, the charge developed by

the

impact of the touch can be lost.
Finally, it seemed that the capacitive
the

greatest

sensor

offered

potential of all available approaches for the

following reasons:

-- 1. Capacitive sensors
ment,

that

is,

the

do not need

additional

equip-

basic insulating sheet and touch

plate are sufficient.

-- 2. Multiplexors for individual sensors can be
or

.are

degenerately

simple

using

row

and

avoided
column

addressing methods described in chapter 3

--

3,

Capacitive

sensors

features identified above.

can

accommodate

all

three

In particular, a measure of

intensity is available since the area ož finger contact
and

corresponding

capacitance

increases

with finger

pressure.

-- 4. Capacitive sensors are very durable since no additional

elements

are

needed

and there is no recovery

2-14

APLNDC00026356

time

phenomenon

involved

as

exists

with

resistive

rubber.

However there are some drawbacks to capacitive sensors.
First

they

require

time

to charge and.discharge. However

these times can be reasonably well controlled.
drawback

is

that

The

second

a capacitive sensor generates radio fre-

quency noise when the tablet is touched. The third

drawback

is low resolution. However the low resolution can be compensated by software technique as discussed in chapter 4. Noise
in

the

radio

problem in

frequency

spectrum,

some .environments,

operation of the tablet.

does

which is potentially a
not

deteriorate

the

Since level of the.noise could not

be known at the time of design, it was not considered

as

a

factor in the choice of sensor.

2.5 CONCLUSION

In this chapter, severai kinds of touch sensitive input
device

have

been

examined

as

a

part

of the process of

developing a flexible multi-purpose input device. Many devices

and

sensor

types

have been analyzed from different

points of view in order to achieve the desired goals.
With respect to the initial .goals of developing a flex-

ible multi-purpose input device,

it seems that the touch

tablet as

does. not žulfill the

conventionally defined,

2-15

APLNDC00026357

requiremenes

of

flexibility

and

aòaptability, out räther

that a fast multiple touch sensitive input

device

(E'MTSID)

must be pursued to meet the real requirements.
In oròer to reach this goal,

hardware

with

a

binary

capacitive

sensor

based

scanning algorithm was chosen for

development.

2-16

APLNDC00026358

•

cuan ER 3

HARDWARE DESIGN AND IMPLDIENTATION

3.1 INTRODUCTION

This

chapter

implementation

of

describes

a

the details of

the

hardware

fast multiple-touch-sensitive input

device ( FMTSID ). The design of the hardware

is

based

on

the hardware requirements identified in the previous chapter
and

on

hardware
and

tradeoffs

between

software

and

basically consists of a sensor

hardware.

The

matrix board,

cow

column selection registers, A/D converting circuits and

a dedicated CPU.
The design of the sensor matrix is based on

nique of

capacitance

measurement between a

and a metal plate. Row selection

more

registers

the

tech-

finger

select

one

tip
or

rows by setting the corresponding bits to a high state

in order to charge up the sensors while the column selection
registers

select

corresponding

one

analog

through

timing

selected

cows

selected

sensors

or

switches

resistors.

and

the
as

more

a

columns

to

by

discharge

turning
the

on

sensors

The intersecting region of the

selected
unit.

columns
A/D

represents

converting

the

circuits

3-1

APLNDC00026359

ce ene discharging time interval of the

selected

sen-

A University of Toronto 6809 board was used as dediced CPU.

The details of the sensor matrix design

section

3.2,

section 3.3.
used

in

with

the

are

given

in

rest of the hardware described in

Section 3.4 describes

the

scanning

sequence

conjunction with the hardware development process

while.section 3.5

concludes

with

a description

of

the

hardware implementation.

3.2 THE SENSOR HATRIX

The design and construction of the sensor matrix board
is

straightforward.

The touch surface of the sensor board

consists of number of small metal-coated

rectangular-shaped

areas serving as sensor plate capacitors.

The design of the

metal plate area of a unit sensor depends on the
capacitance

measurable

change that results when the area is covered by

a finger .tip, and on the resolution thaè.can be implemented.
A 12" by 16" sensor matrix area with a resolution of 32
by

64

sensor.
and

a

was

chosen, resulting in 7 mm by 4 mm area for each.

The estimated capacitance between the sensor
touching

plate

finger separated by 3 mil (0.075 mm) Mylar

insulating coversheet is

3-2

APLNDC00026360

A
-12
7mm*4mm
Cs=e-=3*.8.85*10
[F/m]
=10pF
d
0.075mu·

where

e

is

coversheet,

the
A

dielectric

is

the

area

constant
of

of

the

insulating

the unit sensor and d the .

thickness ož the insulating sheet.
The charge associated with

the

touch

capacitance -is

stored between the sensor plate and the touching finger act-

ing as ground.
sidered

to

be

For this purpose human beings
a

large

charge

can be con-

reservoir. For the static

charge case, a suitable model of a human being is an approximate

100 pF

capacitor with one plate connected to ground.

[tef 3.1] Therefore, it is safe to assume a touch as

ground

reference for measurement of relatively small capacitances.
The 10 pF of sensor capacitance
small

but measurable.

change

is

relatively

For a timing resistor of 100 k, the

time change due to the sensor capacitance change is about
micro-second.

The

tradeoff

between the time taken for the

measurement of the capacitance and the ease
seems

to

bé

obvious.

If

"easy" to measure but it

scanning

procedure.

The

1

the

takes

clock

of

measurement

capacitance is high, it is
longer,

cycle

slowing

used

down

the

to count the

discharging time is also limited by noise in the analog circuits

as

well as by timing limitations ož the TTL circuits

used. With these limitations in

mind,

the

period

of

the

counter clock was chosen to be 100 nano-seconds.

3-3

APLNDC00026361

n order to select a sensor by row and
òiodes

It is referred to

in Fig. 3.2.
ing

back

access,

were used for.each sensor. One diode, connected

: the row line, is used to charge uP
row.

column

to

The CD
the

dropped to zero. The

the

sensors

in

as the Charging Diode (CD) as shown

also serves to block the charge
row

the

line

other

when

diode

flow-

the row line voltage is

called

the

Discharging

Diode(DD), connected to the column.line, enables discharging
of the selected row sensors to a virtual ground. Also the DD
blocks charge flow from the sensors in the selected row to
the sensors in the unselected row during the discharging
period·

The

selection

of roWS, by the row selection pro-

cedure, causes the sensors to be charged. The sensors in the
column

are then discharged through associated timing resis-

tors connected to the column selection switches.
Fig 3.1 (a) shows the components associated with a
selected sensor.
There are two related time periods: One

for the selection of rows ( that i
and

the

other

'
s, tne charging period )
for the selection of columns ( that is, the

discharging period.).. The capacitance is.measured while the
sensor discharges. The signal output during discharging is
shown in Fig. 3.1 (b).
Analytic equations can be derived for the model
ing .that

the

assum-

reverse diode resistance is much higher than

the discharge resistor R and the forward resistance is

muca

3-4

APLNDC00026362

Charging diode

Discharging diode
(C)

a row line
SENSOR

a column line

a column selection

switch
Fig. 3.1 a. A model of a selected sensor in the
sensor agtrix
(A)

(8)

i

i

'

Vt

i

(O

hreshold
Voltage

Pl

P2

y-

instÅntaneous discharging
voltage

... ,

·¯¯¯" - - ---·
'

75 P3

hg. 3.1 b. The timing diagram for discharging time
measurement of a selected sensor as shown above.

APLNDC00026363

column lines
row lines

To

row
selection
register
sensor plates
harging diode
discharging diode

To

column

switch
selection
r
· --

4-timing resistor
--

... ...

column. selection
switches .

To adder

Fig. 3.2 A small sectio¤ of sensor matrix.

APLNDC00026364

n the discharge resistor R.

The derivation is as

a discaarging voltage ( V ) is given by
-t

V=Vi*exP(--1
T

where

Vi

is

the .instantaneous

initial

voltage

of

the

discharging period and T is the time constant.

T is given by
T=R(Cs+Cr)

where Cs is the sensor capacitance and Cr

is

the

reverse

bias capacitance of the diode.
The voltage Vi can be found from
Cs
Vi=(

Os-Of
)(

Cs+Cr

)(Vcc-Vd)

Os

where Os and Of are respectively the charges stored
sensor

and

the

forward

biased

diode

discharging period begins, and Vcc and Vd
the

just
are

in

the

before

the

respectively

high state voltage for CHOS and the diode voltage drop.

In the equation for Vi, the first factor is associated with
charging

up a reverse biased diode while the second factor

results from the charge in the forward biased diode

stored

3-5

APLNDC00026365

the charging period.

The.discharge time is measured by the comparison with a
chgeshold voltage ( Vt ) and it is given by

Vt
Ts=-T1n(---)
Vi

From these analytic equations,

sions

the

following

conclu-

relating to the selection of appropriate voltage lev-

els and .the diode type can be made.
-- 1. The higher the Vec, the less sensitive is the measurement to the threshold voltage at V = Vt where the Vt

= aVcc and the sensitivity,that is the derivative of
with respect to t,

V

is -avec/T.

-- 2. The smaller the reverse bias diode capacitance,

the

higher the resulting Vi and the less time it takes to
measure the same sensor capacitance.
-- 3. The smaller Of can be made,-the higher Vi will be.
The first implication is the choice of
interface

the

sensor

to

To use CMOS logic directly connected

board which is prone to high static voltage

from touch, the circuitry must be protected.

High

voltage

to

bypass

logic

sensor matrix using high logic voltages with

Vec equal to 15 volts.

to the

CMOS

diodes

are

connected

negative

each

row

3-6

APLNDC00026366

f

line(charging source) for this reason.
The second implication is the use of diodes with
reverse

capacitance.

small

The diode IN 4148 was chosen for low .

capacitance, low cost, and

availability. The

reverse

clas

capacitance of this dioòe is specified as 4 pF.

The third implication relates directly to

the

forward

current of the diode since Of = Cf.* Vd = k * Id * Vd, where
Cf is the forward capacitance, Vd is the diode voltage drop,
Id

is

the

diode

forward

current and k is some constant.

Furthermore, since Id = (Vcc - 2*Vd)/R, the Id selected

is

then interrelated with the timing resistor chosen.

Further analysis of the sensor matrix is
there

are

board.

2048

such

Accordingly

the

unit

of

interest:

sensors implemented on the P.C

analysis

is

rather

complicated

oecause the rows and columns are electrically not completely
separated. A small section of the sensor
tion

is

shown

in

matrix

Fig. 3.2 for illustration.

bias capacitance couples the sensors in a

configuraThe reverse

column.

Moreover

there exist capacitances between columns due to the physical

configuration of the sensor plates and wires and due to
parasitic

the

capacitances in the circuit, and these couple the

sensors in a row.

The first of these coupling is seen to be

unavoidable while effort was taken to reduce the second.

A simple

column sensor

array

has

been

analyzed. as

APLNDC00026367

shown

in

here.

The analysis is based on an effort to obtain Vi,

instant

appendix

initial

A.

Only the results will be discussed

voltage

in

the discharge period, r,

the

the

ratio of the sensor capacitance over the surrounding capacitance, and m, the separation parameter in the rows.
The instantaneous discharging voltage Vi for a case

when

a

selected sensor.is touched, is given by
st*a÷0.5*(n-1)-f*b
Vi-

(Vcc-2*Vd)

st+0.S*(n+3)

where a = (Vcc-Vd)/(Vcc-2*Vd), b=Vd/(Vcc-2*Vd), f=Cf/Cr, and
st=Cal\Ct/Cr.

The ratio of the sensor capacitance to the intrinsic capaci-

tance of the surroundings, r, is
st

n+1

.st

2

The separation parameter m
sensors

is the

number

which must be touched, to cause

selecteä, sensor to report as "touched".
equations

for

of

non-selected

a non-touched, but
Appendix

A shows

derivation of this parameter and its evalua-

tion by computer iteration in terms of variables such as t'ne
ratio

of

Cs/Cr

and

Cf/Cr.

When Cs/Cr = 2.5 and Cf/Cr =

12.5, the separation parameter m is about 8, and when

Cs/Cr

3-8

APLNDC00026368

5.ô and Ci/Cr = 12.5 the m is about,25.

The firse result

oplies that if more than 8 sensors are touched in a column,
caen

the result will be a wrong report that all the sensors

in the column have been touched.

that if more

The second result

implies

than 25 sensors are touched in a column, the

result will be a report that all the sensors in
have been touched.

the column

Nevertheless, all of the analysis for .

the single selected sensor model is still

valid with some

complication.
The analysis becomes more complicated when the
ters

for

rows

and

column

are incluòed in the equations.

Since the operational amplifier adds currents from
columns

and

oy

selecteä

consequently the discharging time increases by

l+1n(2)/a, where a = ln(Vi/Vt), when the number
increases

parame-

factor

of

two,

the

of

columns

režerence values
of

expected to be increased by the

factor

In(10/3) = 1.2 correspondingly.

However, an increase in-the

number of rows in a group is not expected
reference

values

because

selected reverse bias diodes

charge stored

the

charge

becomes

1.57

to
stored

smaller

žor a

are

increase

=

the

in ene nonwhereas

the

in the selected forward bias diodes remain

constant during charging period and consequently Vi

becomes

smaller.

Efforts have been made to separate the columns as much
as possible. However there still will be some coupling capa-

3-9

APLNDC00026369

ces between columns

due

to

physical

adjacency;

but

effects are considered to be minimal.

3.3 INTERFACE CIRCUIT DESIGN AND INPLEMENTATION

Interfacing between the sensor matrix and the dedicated
CPU requires three main circuit blocks: row selection registers, column switch selection registers and A/D

converting

circuits. The CPU selects the row or rows of a sensor group,
initiating charging of all the associated sensors.

After

a

charging interval, the CPU discharges the selected column or
columns corresponding to a
group

of

sensor

group

by

connecting

a

discharge resistors whose current is summed via a

high slew rate operational amplifier.
There is tradeožf between the scheme using a.single bit
for

each

row

and one using decoding circuits to implement

binary addressing suited to the.binary
The .bit

per

scanning

row scheme requires 32 bits of register while

binary coding needs 6 bits of register since only
.

patterns

of

algorithm.

sensor

scanning algorithm.

grouping

32 * 2 -1

exit according to the binary

However, the first scheme was chosen

because it is ultimately flexible, that is, it allows one to
i¤plement "all" scanning ¤odes by means
enanges

can

be

implementation of

L

of

software.

Thus

easily made in the case of difficulty with
a

particular

software

algorithm.

The

3-10

APLNDC00026370

oced

prototype uses fout 8 bit registers with a com-

reset signal for row selection.
For the same reasons sufficient column switch selection
agisters

are

provided

pattern through software.

so that one can generate any group

However, to reduce the number

of

chips on the board, four switches are controlled by each bit
resulting in žour simultaneous analog signals
tating

four

counters.

However

and

as a result

latches are needed to control 64 swicches.

necessi-

only 2 8-bit

The four sets of

data are provided to the CPU after each scan. These data are
manipulated by software in.correspondence with the
resolution mode.

selected

This implies the hardware itself acts as

an array of 32 by 16 bits while the software emulates 32
64

bits

of

by

scanning resolution. The scanning algorithm is

explained in chapter 4.
The charges stored in the

through

the

selected

cow(a)

ilow

down

selected switches to the virtual ground of the

fast operational amplifier. All the discharging currents are

correspondingly added to produce a signal from which the
discharging time of all the selected sensors can be found by
comparison with a threshold voltage. The output of the nega-

tive voltage comparator is fed to the enable signal
counter

of

the

and to the data bus as a status bit for the counter

readiness. All the counters are reset when the row selection
registers

are

deselected in order to initiate tae counting

APLNDC00026371

process.
The clock rate (10
correspond
But,

of

MHz)

allows

about

10

counts

to

to the sensor capacitance change due to a touch.
course,

the

capacitance

of

all

the

circuitry

attached to the column line during the discharging period is
much larger than the sensor capacitance. Before scanning the
tablet for a touch, the dedicated CPU scans it completely in
all possible resolution modes

so

obtained

when not touched. The

are stored as references.

values

Touches are identi-

fied by the differences between the reference values and the
values measured during use.
The capacitance change corresponding to

the

touch

by

more than one finger when the resolution is very small, that
is, when the area of the sensors selected is large, is
very

large..

Thus the number of bits in the counter should

be enough to measure the maximum capacitance.
unnecessary

also

However it is

either to have enough number of oita to measure

the entire capacitance

including

tances,

the corresponding "complete" counter

or

to

store

values as references.
bit

the

the

capaci-

It is necessary to have only one more

than the number of bits required

change in

surrounding

capacitance

rather

to count the value of
than

complete

counter

values in order to measure difference of the capacitance due
to touch.
space

Thus only an 8 bit counter was

allowed

for

an

extra

implemented

with

4 bit counter in case that a

3-12

APLNDC00026372

eater number of bits is found to be necessary.
counter
(

eaa'oles

the

measurement

of

a

The 8

7 bit capacitance

caange regardless of the degree of overflow in tae
This

means

127, the difference can be obtained without

For exampler a counter value 4 is larger than £8

if the difference is less than 7f in hexadecimal;
words,

an

ate.

counter.

that if the difference, touched to non-touched,

does not exceed
ambiguity.

bit

in

other

unsigned 8 bit comparison would not be appropri-

Therefore the counter does not need to accommodace the

entire

discharging

time including the time due to the aur-

rounding capacitance, which may require more
Some

manipulation

above.

than

8

bits.

is done in software to utilize the žacts

A complete analysis is given in appendix B.

The remaining circuits are for-shifting CMOS levels
TTL

level

and

for òecoding addresses. Eight addresses are

decoded with a R/W signal. One write address is used
single

to

register

for

a

whose output controls the discharge of all

the senbor matrix at once, the grounding of the ground strip
on

the

board

for

template

recognition

applications

as

described below, and as well as controls three LED outputs.

A metal strip is located on one side of the touch
face

of

the

board.

This

strip is a programmable ground

strip which can be grounded to allow a metal-coated
on .the
scanned.

back

side

sur-

of the template shown in Fig.3.3

pattern
to be

It can be angrounded for normal binary scanning so

3-13

APLNDC00026373

•.et 1 co. til

°2dot pattern

Template

touch Frees

pr ogre mmt ble
ground strip
----· sensor vret

Touch sensitive tablet
"ig. 3.5 Template and touch sensitive tablet.
The template pattern lies on the sensor cre:.
Its metal coating touches the ground strip
which is grounded .to initie te recognition of
the template.

APLNDC00026374

esat the "touch" by tae pattera can be ignored. Otherwise it
increases the time to scan all the poir.ts.on the touch

sur-

face including the unneeded points from che template because
the binary scanning time is

directly

proporcional

to

tÂe

numoer of points on the tablet.

3.4 THE HARDWARE SCANNING SEQUENCE

This section describes the reading

sequence

for

data

from the sensor matrix board.
A block diagram of the
hardware circuit is shown in Fig. 3.4 to aSSist the reaâer.
The sequence is as follows.
-- 1. Reset the row selection registers. That

is,

ground

the inPuts.to the sensor matrix.
¯- 2. Discharge all the sensors directly

to

ground

(out

noc through R) for aoout 2 microseconds.
-- 3. Select the row selection registers with an appropriate bit pattern,
-- 4. Select column switches by turning on the appropriate
bit

pattern

in

the column switch selection registers

about 4 micro-seconds to stabilize the sensor charge.
-- 5. Roset the row selection registers and the une output
counters together to initiate counting of the discha g-

3-14

APLNDC00026375

SENSOR

ROW
SELEC'JIGE

f

REGISSERS

MATRIX

COMMON RESET &
RE0ISTER SELECT SI

COLUMN

SWITCHES

·

¿L...

LS

OUNTE S

COLUW SETCH SELECHON
RJGISTERS
COUNTER SELECT S I:GHAM

2
SENSOR DISCHARGE SIGNAL

ADDRESS

DECODER
DDRESS BUS

'

DATA BUS

CPU

ADDRESS ggg

Fig. 3.4 Block diagram of the hardware.

APLNDC00026376

ing time.

-- 6. Wait until the counters are ready

oy

reading

the

status bits.

-- 7. Read the counters.
The bit patterns in the row selection register
the

column

in

switch selection register represent the row and

column addresses respectively. These, however,
converted

and

to

a convenient

routine.

to

be

form corresponäing to physical

placement which is understandable to
interfacing

have

the

user

or

to

the

This process is described in the next

chapter,

3.5 CONCLUSIONS

In

this

chapter,

tradeoffs

between

software

and

hardware have been discussed while introducing the design of

the sensor board and its interfacing circuits.

A prototype

tablet has been implemented .and tested. There were difficalties but all have been sufmounted.

The detailed results

ož

performance testing are described in the chapter 5.

3-15

APLNDC00026377

for(i=0; i<3; i÷÷)
switen(i) (

case 0: bs(coladr+1,cowadt,1eveltelevelc);
break;
case.1: bs(coladt,cowadr+1,levelr,1evelc)i
break;

case 2: bs(coladr+1,cowadr+1,1evelt,levelc);
break;
default: break;

The oinary scanning algorithm is

in assembler

actually

im'plemented

in a non-recursive way; however the structure

and the algoritna have not been cha¤ged from the representaclon aoove.

This algorithm and the modified linear scanning

algorithm are very sensitive to the values of the thresholds
for each level. Thus detecting very small contact areas over
a large sensor group area is rather difficult.
if

the

threshöld

for

the

top level is high then a small

intensity of touch may not be detected;
low,

then

the

search

whereas

iž it

is

may not be successful. Consequently

this would slow down.the scanning procedure
number

Accordingly

sinco

a

large

of unsuccessful trys at the bottom level ( caused by

low threshold in the higher levels ) delays the scan of

the

actual touch points.

4.6 COMPENSATION FOR LOW RESOLUTION HARDWARE

It may seem that the resolution of the hardware is .too
low

for

use

in

graphics

applications.

However

touch

4-10

APLNDC00026378

incensity and multi-touch sensitivity òan be used to enhance

resolution.

.This is possible because the conter 0ž a touch

can be most accurately estimated by an interpolation utilizing

the

values

of the adjacent sensor intensities.

For a

simple example, consider the estimation of'the center of the

touch by an interpolation method as follows:
SupPose the touched point is (i,j) and its
is

z(irj).

Let

intensity

the dx and dy be the relative position of

the interpolation to the integer position (irj).
dx,

and

value

Then

the

dy can be ottained from the values of the adjacent

intensities as follows.
I(-1,+1) (z(i+k,j+1) -z(i+krj-1)
(-1,+1)I(-1,+1)(=(i+k,j+1))
dy-

(-1,÷l)(z(i+1,j+k)-z(i-1,j+k))
T.(-1,+1) Ji(-1,+l)(z(i+k,j+1))

Thus the estimated center of touch is (i+dx, j+dy).
A simple case is shown in Fig 4.5 where possible inter-

polation

points

are

shown when

1, 2, 3, 4, or 5 bits of

intensity are provided from two adjacent sensors.
ture shows that

The pic-

incerpolation points are not evenly popu-

lated and that tne scheme does not give good resolution even
if

a

fairly

high

number

Therefore it may be good
point

of intensity bits are provided.

idea

to

map

each

interpolation

to another domain which gives eve ly populated points
4-11

APLNDC00026379

.

0.0

liid

.o
1 bit

intensity

2 bits

intensity

3 bits

intensity

4 bits

intensity

5 bito

intensity

Fig. 4.5 Centers of pressure interpolated from two sensors with
the number of available bits for pressure being 1, 2, 3,
4, and 5 from left to right.

Each line represents a possible interpoletion point.

APLNDC00026380

for possible combinations of the intensities from two
cent

sensors.

adja-

However such an interpolacion mapping scheme

has not been implemented due to complications

involved

for

more than two sensors.
However the interpolation should be performed in
of

terms

the physical center of the touch shape. Since the .inten-

sity given by the capacitance measurement

is

dependent

of

tae area of touch on the cover of sensor plate, the accurate
center of a touch is more dependent of the size of the touch
relative to the size of the sensor area as well as the shape
of sensor plate.
For the implementation, however, it uses direct
polation

scheme for a few.cases.

One of interest is inter-

polating 3 by 3 sensors with a touched point in

and

inter-

the

center

the other is interpolation of all points on the tablet.

The later one obviously gives highest resolution but it simply emulates a single touch tablet with a high resolution.
The .software in the.dedicated CPU utilizes the communication with the host computer to accommodate the interpolation scheme in the host computer.

4.7 SEQUENCE OF OPERATIONS

The programs in the .dedicated processor

are

sequenced

4-12

APLNDC00026381

.

REFERENCES

Touch Sensitive Tablet as E·acensible Devicû"
di
W.Buxton,
G.Fedorkow,
L.Sasaki,
and
X.C.Smith,

Computer

Systems

Research

Group,

1983

.:1.2

"A Touc'n-Sensitive InPut Device".,

of

Proceedings

the Fifth International Conference on Com-

Puter Music, North Texas State University, Denton, Texas, November, 1981,

of2.0]

"Why Touch Sensing" by Louise

C.Shaw,

Datama-

tion, August 1980, p138-p141
222.1]

United State Patent

3,798,370

Electrographic .Sensor

for

March

19,1974,

Determini¤9 Planar

Coordinates and 3,911,215 October, 7, 1975,
Discriminating Contact Sensor by George S.
Hurstr Elographics, Incorporated,

22.3)

"New Touch Screen Computer" by George Mitchell,
ComPuters and Electronics, December,1983, p57 p66

R-1

APLNDC00026382

yef2.4]

Touch Screen

19iti2er

Data

Sheet· from

TSD

Display Product Inc•, 1982

(ref2.5] .

A Flexible

Thesis,

Human

Machi e

Interfacer

M.A.Sc.

University of Toronto, 1982 by Nimish

Hetha

(ref2.6J

TASA Model: x-y 3600 and X-y controller, Model:
FR-105 Data Sheet 1980

(ref2.7J

Pressure-Sensitive Conductive Rubber Data Sheet
by JSR PCR 1981

ref2.8J

A circuit diagram drawn by FedockoW

in

March,

1981, University ©2 Toronto
ref3.1]

:ef5.l]

Curing
Static
Electricity"
by
Elliott
S.Kanter, Raðio Electronics, Sept•· 1984

Manipulating Simulated Objects With

Gestures

Real-world

Si¤9 a Force and Position Sensitive

Screen by Margaret R.Mi SkY, ComPuter
Volume 18, Number 3 JulY 1984

ef6.l]

Graphics

Solders and Soldering by Howard H.
McGraW-Hill, 1979, p252 - p257

Hanko,

R-2

APLNDC00026383

This Page is Inserted by Ir vv Indexing and Scanning
Operations and is not part of the Official Record

BEST AVAIL ABLE IMAGES
Defective images within this document are accurate representations of the original
documents submitted by the applicant.

Defects in the images include but are not limited to the items checked:
ACK BORDERS
O IMAGE CUT OFF AT TOP, BOTTOM OR SIDES
ED TEXT OR DRAWING
O BLou w wD OR ILLEGIBLE TEXT OR DRAWING
SKEWED/SI ANTED IMAGES
OR OR BLACK AND wm1E PHOTOGRAPHS
GRAY SCALE DOCUMENTS
INES OR MARKS ON ORIGINAL DOCUMENT
O REFERENCE(S) OR EXHIBIT($) SUBm- a « D ARE POOR QUALITY

OO · -R:

TifA GES sus BEST AVA TI.ABLE COPY.
As rescanning these documents will not correct the image
problems checked, please do not report these problems to
the if w Image Problem Mailbox.

APLNDC00026384

Application Serial No. 11/278,080 filed on 03/30/2006

DOCKET NO: P3764US1
(119-0077US)

APPLICATION
FOR
UNITED STATES Lt-

TITLE:

ERS PATENT

Force Imaging Input Device and System

INVENTORS: Steve Hotelling and Brian Q. Huppi

Date: March 30, 2006

Preoared bv
WONG, CABELLO, LUTSCH, RUTHERFORD & BRucCULERI, L.L.P.

Houston, Texas
(VOICE) 832 i ll 2400
(FACSIMILE)832-446-2424

Austin, Texas
(VolcE) 512-473-2550
(FACSIMILE) 512-473-2555

BEST AVAILABLE COPY
APLNDC00026385

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

FORCE IMAGING INPUT DEVICE AND SYSTEM

Backgroppd

[0001]

The invention relates generally to electronic system input devices and,

more particularly, to force imaging and location-and-force imaging mutual capacitance

systems.
[0002]

Numerous touch sensing devices are available for use in computer

systems, personal digital assistants, mobile phones, game systems, music systems and
the like (Le., electronic systems). Perhaps the best known are resistive-membrane
position sensors which have been used as keyboards and position indicators for a
number of years. Other types of touch sensing devices include resistive tablets, surface
acoustic wave devices, touch sensors based on resistance, capacitance, strain gages,
electromagnetic sensors or pressure sensors, and optical sensors. Pressure sensitive
position sensors have historically offered little benefit for use as a pointing device (as
opposed to a data entry or writing device) because the pressure needed to make them
operate inherently creates stiction between the finger and the sensor surface. Such
stiction has, in large measure, prevented such devices from becoming popular.
[0003]

Owing to the growing popularity of portable .devices and the attendant

need to integrate all input functions into a single form factor, the touch pad is now one
of the most popular and widely used types of input device. Operationally, touch pads
may be categorized as either "resistive" or "capacitive." In resistive touch pads, the pad
is coated with a thin metallic electrically conductive layer and resistive layer. When the

-1-

APLNDC00026386

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

pad is touched, the conductive layers come into contact through the resistive layer
causing a change in resistance (typically measured as a change in current) that is used
to identify where on the pad the touch event occurred. In capacitive touch pads, a first
set of conductive traces run in a first direction and are insulated by a dielectric insulator
from a second set of conductive traces running in a second direction (generally
orthogonal to the first direction). The grid formed by the overlapping conductive traces
create an array of capacitors that can store electrical charge. When an object is brought

into proximity or contact with the touch pad, the capacitance of the capacitors at that
location change. This change can be used to identify the location of the touch event.
[0004]

One drawback to using touch pads as input devices is that they do not

generally provide pressure or force information. Force information may be used to
obtain a more robust indication of how a user is manipulating a device. That is, force

information may be used as another input dimension for purposes of providing
command and control signals to an associated electronic device. Thus, it would be

beneficial to provide a force measurement system as part of a touch pad input device.
Summarv

[0005]

In one embodiment the invention provides a force sensitive touch pad

that includes first and second sets of conductive traces separated by a spring
membrane. When a force is applied, the spring membrane deforms moving the two sets
of traces closer together. The resulting change in mutual capacitance is used to
generate an image indicative of the location (relative to the surface of the touch pad)

-2-

APLNDC00026387

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKEY NO: P3764US1
(119-007705)

and strength or intensity of an applied force. In another embodiment, the invention
provides a combined location and force sensitive touch pad that includes two sets of
drive traces, one set of sense traces and a spring membrane. In operation, one of the
drive traces is used in combination with the set of sense traces to generate an image of
where one or more objects touch the touch pad. The second set of drive traces is used
in combination with the sense traces and spring membrane to generate an image of the
applied force's strength or intensity and its location relative to the touch pad's surface.
Force touch pads and location and force touch pads in accordance with the invention
may be incorporated in a variety of electronic devices to facilitate recognition of an
increased array of user manipulation.
[0006]

In yet another embodiment, the described force sensing architectures

may be used to implement a display capable of detecting the amount of force a user
applies to a display (e.g., a liquid crystal display unit). Display units in accordance with
this embodiment of the invention may be used to facilitate recognition of an increased
array of user input.
Brief pewr!Rtion of the Drawings
[0007]

.

Figure 1 shows, in exploded perspective view, a force detector in

accordance with one embodiment of the invention.
[0008]

Figures 2A and 28 show, in cross-section, an unloaded (A) and loaded (B)

force detector in accordance with FIG. 1.

-3-

APLNDC00026388

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-007705)

[0009]

Figure 3 shows, in block diagram form, a force detection system in

accordance with one embodiment of the invention.
[0010]

Figure 4 shows, in block diagram form, a more detailed view of the force

detection system in accordance with FIG. 3.
[0011]

Figure 5 shows, in cross-section, a location and force detection device in

accordance with one embodiment of the invention.
[0012]

Figure 6 shows, in cross section, a location and force detection device in

accordance with another embodiment of the invention.
[0013]

Figure 7 shows an exploded view of drive and sense traces in accordance

with FIG. 6.

[0014]

Figures 8A-8C show various views of a location and force detection device

in accordance with still another embodiment of the invention.

[0015]

Figures 9A-9C show various views of a location and force detection device

in accordance with yet another embodiment of the invention.
[0016]

Figures 10A and 10B show, in cross section, a location and force detection

device in accordance with another embodiment of the invention.
[0017]

Figures 11A-11C show various views of a spring membrane in accordance

with another embodiment of the invention.
[0018]

Figures 12A and 128 show, in block diagram form, a force detection

display system in accordance with one embodiment of the invention.

.4.

APLNDC00026389

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

Detailed Descriotion

[0019]

The following description is presented to enable any person skilled in the

art to make and use the invention as claimed and is provided in the context of the
particular examples discussed below (touch pad input devices for personal computer
systems), variations of which will be readily apparent to those skilled in the art.
Accordingly, the claims appended hereto are not intended to be limited by the disclosed
embodiments, but are to be accorded their widest scope consistent with the principles
and features disclosed herein. By way of example only, force imaging systems in
accordance with the invention are equally applicable to electronic devices other than
personal computer systems such as computer workstations, mobile phones, hand-held
digital assistants and digital control panels for various machinery and systems
(mechanical, electrical and electronic).
[0020]

Referring to FIG. 1, the general concept of a force detector in accordance

with the invention is illustrated as it may be embodied in touch pad device 100. As
illustrated, force detector 100 comprises cosmetic layer 105, sense layer 110
(including conductive paths 115 and electrical connector 120), dielectric spring layer
125 (including spatially offset raised structures 130), drive layer 135 (including

conductive paths 140 and electrical connector 145) and base or support 150. (It will
be understood by those of ordinary skill in the art that connectors 120 and 145
provide unique connections for each conductive trace on layers 110 and 135
respectively.)

-5-

APLNDC00026390

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

[0021]

Cosmetic layer 105 acts to protect other elements of the system from

ambient conditions (e.g., dust and moisture) and, further, provides a surface through

which users interact with detector 100. Conductive paths 115 on sense layer 110 are
arranged so that they overlap conductive paths 140 on drive layer 135, thereby
forming capacitors whose plates (conductive paths 115 and 140) are separated by
sense layer substrate 110, dielectric spring layer 125 and raised structures 130.
Dielectric spring layer 125 and raised structures 130 together create a mechanism by
which sense layer 110's conductive paths 115 are brought into closer proximity to
drive layer 135's conductive paths 140 when a force is applied to cosmetic layer 105.
It will be recognized that this change in separation causes the mutual capacitance
between sense layer and drive layer conductive paths (115 and 140) to change
(increase) - a change indicative of the amount, intensity or strength of the force
applied to cosmetic layer 105. Base or support layer 150 provides structural integrity
for force detector 100.

[0022]

Referring to FIG. 2A, a cross-sectional view of force detector 100 is

shown in its unloaded or "no force" state. In this state, the mutual capacitance between

sense layer 110 and drive layer 135 conductive paths (115 and 140) results in a
steady-state or quiescent capacitance signal (as measured via connectors 120 and 145
in FIG. 1). Referring to FIG. 2B, when external force 200 is applied to cosmetic layer
105, dielectric spring layer 125 is deformed so that sense layer 110 moves closer to
drive layer 135. This, in tum, results in a change (increase) in the mutual capacitance
between the sense and drive layers - a change that is approximately monotonically
-6-

APLNDC00026391

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-007705)

related to the distance between the two and, therefore, to the intensity or strength of
applied force 200. More specifically, during operation traces 140 (on drive layer 135)
are electrically stimulated one at a time and the mutual capacitance associated with the
stimulated trace and each of traces 115 (on sense layer 110) is measured. In this way
an image of the strength or intensity of force 200 applied to cosmetic layer 105 is
obtained. As previously noted, this change in mutual capacitance may be determined
though appropriate circuitry.
[0023]

Referring to FIG. 3, a block diagram of force imaging system 300 utilizing

force detector touch pad 100 is shown. As illustrated, force imaging system 300
comprises force detector 100 coupled to touch pad controller 305 through connectors
120 (for sense signals 310) and 145 (for drive signals 315). Touch pad controller
305, in turn, periodically sends signals to host processor 320 that represent the
(spatial) distribution of force applied to detector 100. Host processor 320 may
interpret the force information to perform specified command and control actions (e.g.,
select an object displayed on display unit 325).
[0024]

Referring to FIG. 4, during operation drive circuit 400 in touch pad

controller 305 sends ("drives") a current through drive signals 315 and connector 145
to each of the plurality of drive layer conductive paths 140 (see FIG. 1) in turn.
Because of capacitive coupling, some of this current is carried through to each of the
plurality of sense layer conductive paths 115 (see FIG. 1). Sensing circuits 405 (e.g.,
charge amplifiers) detect the analog signal from sense signals 310 (via connector 120)
and send them to analysis circuit 410. One function of analysis circuit 410 is to convert
-7-

APLNDC00026392

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

the detected analog capacitance values to digital form (e.g., through A-to-D
converters). Another function of analysis circuit is to queue up a plurality of digitized
capacitance values for transmission to host processor 320 (see FIG. 3). Yet another
function of analysis circuit is to control drive circuit 400 and, perhaps, to dynamically
adjust operation of sense circuits 405 (e.g., such as by changing the threshold value at
which a "change" in capacitance is detected). One embodiment of controller 305
suitable for use in the present invention is described in US patent application entitled
"Multipoint Touch Screen Controller," serial number 10/999,999 by Steve Hotelling,
Christoph Krah and Brian Huppi, filed 15 March 2006 and which is hereby incorporated
in its entirety.
[0025]

In another embodiment, a force detector in accordance with the invention

is combined with a capacitive location detector to create a touch pad device that
provides both location and force detection. Referring to FIG. 5, combined location and

force detector 500 comprises cosmetic layer 505, circuit board or substrate 510
(including a first plurality of conductive drive paths 515 on a first surface and a plurality
of sense paths 520 on a second surface), dielectric spring layer 525 (including
alternating, or spatially offset, raised structures 530), drive layer 535 (including a
second plurality of conductive drive paths) and base or support 540. In one
embodiment, conductive drive paths 515 and 535 are laid down on substrate 510 and
support 540 respectively to form rows and sense conductive paths are laid down on
substrate 510 to form columns. Accordingly, during operation first drive paths 515 are
driven (one at a time) during a first time period and, during this same time, sense paths
-8-

APLNDC00026393

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

520 are interrogated to obtain an image representing the location of one or more
cosmetic layer touches. Similarly, second drive paths 535 are driven (one at a time)
during a second time period and, during this same time, sense paths 520 are again
interrogated to obtain an image representing, this time, the strength or intensity of the
force applied to cosmetic layer 505. The operation of computer input devices (e.g.,
touch pads) for touch detection based on the principle of mutual capacitance is
described in US patent application entitled "Multipoint Touchscreen" by Steve Hotelling,
Joshua A. Strickon and Brian Q. Huppi, serial number 10/840,862 and which is hereby
incorporated in its entirety.
[0026]

Referring to FIG. 6, location and force touch pad 600 in accordance with

another embodiment of the invention is shown in cross section. In this embodiment,
cosmetic layer 605 comprises a polyester or polycarbonate film. Layer 610 comprises
an acrylic-based pressure sensitive or ultraviolet light cured adhesive. Layer 615
functions as a two-sided circuit board that has a first plurality of conductive drive traces
620 oriented in a first direction on a "top" surface (Le., toward cosmetic layer 605)
and a plurality of conductive sense traces 625 oriented in a second direction on a
"bottom" surface. In one embodiment, circuit substrate layer 615 comprises a low
temperature plastic or thermoplastic resin such as polyethylene terephthalate ("PET").
In this embodiment, drive traces 620 and sense traces 625 may comprise printed
silver ink. In another embodiment, circuit substrate layer 615 comprises a flexible

circuit board, or fiberglass or glass and drive and sense traces (620 and 625) comprise

Indium tin oxide ("ITO") or copper. Layer 630, in one embodiment, comprises a

APLNDC00026394

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-OO77US)

layered combination consisting of adhesive-PET-adhesive, where the adhesive

components are as described above with respect to layer 610. Layers 635, 640 and
645 comprise PET of varying thicknesses. As shown, the "bottom" surface of layer 640
has affixed thereon a second plurality of conductive drive traces 650 oriented in
substantially the same orientation as first conductive drive traces 620. Raised and
spatially offset support structures 655 and layer 660 also comprise a layered
combination consisting of adhesive-PET-adhesive (similar to layer 630, see above).
Layers 605-660 are affixed to and supported by base or stiffener plate 665. For
example, in a portable or notebook computer system, base 665 could be formed from a
rigid material such as a metal stamping that is part of the computer system's frame.
Similarly, base 665 could be the internal framing within a personal digital assist and or
mobile telephone. Table 1 identifies the thickness for each of layers 600-660 for one
embodiment of touch pad 600.

Table 1: Dimensions for Illustrative Touch Pad 600
Layer

Material

Thickness (mm)

605

Polyester, polycarbonate film, glass or ceramic

0.3

610

Pressure sensitive adhesive ("PSA") or ultraviolet
("UV") light cured adhesive

0.05

615

PET

620

Silver ink, copper, Indium tin oxide

0.006

625

Silver ink, copper, Indium tin oxide

0.006

630

Layered PSA-PET-PET

0.075 ± 0.02

0.03 ± 0.01

- 10 -

APLNDC00026395

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

Table 1: Dimensions for Illustrative Touch Pad 600

Layer

Material

Thickness (mm)

635

PET

0.075 ± 0.02

640

PET

0.1 ± 0.02

645

PET

0.125 ± 0.02

650

Silver ink, copper, Indium tin oxide
Layered:

0.006
0.025 ± 0.01

PET

0.1 ± 0.02

PSA

655

PSA

0.025 ± 0.01

Active touch pad surface: 271 mm × 69 mm
No of drive traces (620 and 650): 13
Number of sense traces (625): 54

Pixel separation: 5 mm

[0027]

In operation touch pad 600 measures the change (e.g., decrease) in

capacitance due to cosmetic layer 605 being touched at one or more locations through
the mutual capacitance between drive traces 620 and sense traces 625. In a manner
as described above, touch pad 600 also measures forces applied to cosmetic layer as
sense traces 625 and drive traces 650 are brought into closer proximity through the
measured change (e.g., increase) in mutual capacitance between them. In this
embodiment, raised structures 655 are used on both sides of the second layer of drive
traces (650) to provide additional movement detection capability.

[0028]

During measurement operations, each of drive traces 620 are stimulated

in turn and, simultaneously, the change in mutual capacitance between drive traces

- 11 -

APLNDC00026396

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

620 and sense traces 625 is measured. Once each of drive traces 620 have been

stimulated (and the corresponding change in capacitance measured via sense traces
625), each of drive traces 650 are driven in turn and sense traces 625 are used to
determine the change in mutual capacitance related to force (that is, the mutual
capacitance change between traces 625 and 650 due to an applied force). In this
manner, images of both the "touch" input and "force" input to cosmetic layer 605 can
be obtained.

[0029]

One of ordinary skill in the art will recognize that the above-described

"scanning" sequence is not required. For example, drive traces 620 and 650 could be
stimulated in overlapping fashion such that a first trace in drive traces 620 is
stimulated, followed by a first trace in drive traces 650, followed by a second trace in
drive traces 620 and so on. Alternatively, groups of traces in drive traces 620 could be
stimulated first, followed by a group of traces in drive traces 650, and so on.
[0030]

In one embodiment drive traces 620 (associated with touch location

measurement operations) use a different geometry from drive traces 650 (associated
with force measurement operations) and sense traces 625 (used during both location

and force measurement operations). Referring to FIG. 7, it can be seen that drive
traces 620 utilize conductive traces that employ internal floating plate structures 700
and, in addition, are physically larger than either the conductive traces used in sense
625 and drive traces 650 (both of which, in the illustrated embodiment, have the same
physical size/structure). It has been found that this configuration provides increased

- 12 -

APLNDC00026397

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

sensitivity for determining where one or more objects (e.g., a finger of stylus) touch, or
come into close proximity to, cosmetic surface 605.
[0031]

Referring to FIG. 8A, in another embodiment of a combined touch and

force sensitive touch pad in accordance.with the invention (touch pad 800), raised
structures 655 may be replaced by beads or polymer dots 805 (also referred to as

rubber or elastomer dots). In this embodiment, beads 805 operate in a manner similar
to that of raised structures 655 (see FIG. 6). As shown, beads 805 rest on a thin
adhesive layer 810 and are sized to keep layers 630 and 640 at a specified distance
when no applied force is present. One illustrative layout and spacing of beads 805 is
shown in FIGS. 8B (lop view) and 8C (cross-section). Table 2 identifies the approximate

dimensions for each component of touch pad 800 that is different from prior illustrated
touch pad 600.

Layer

Table 2: Dimensions for Illustrative Touch Pad 800
Material
Thickness (mm)

805

Rubber or polymer (e.g., elastomer)

810

Pressure sensitive adhesive ("PSA") or ultraviolet
("UV") light cured adhesive

0.015

a

Column bead separation

1.0

b

Row bead separation

5.0

c

Bead offset

2.5 ± 0.15

d

Bead height

0.15

Active touch pad surface: 271 mm × 69 mm

- 13 -

APLNDC00026398

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

Table 2: Dimensions for Illustrative Touch Pad 800
Layer

Material

Thickness (mm)

No of drive traces (620 and 650): 13
Number of sense traces (625): 54
Pixel separation: 5 mm

[0032]

Referring to FIG. 9A, in yet another embodiment of a combined touch and

force sensitive touch pad in accordance with the invention (touch pad 900), a single

layer of deformable beads or elastomer dots 905 are used. In touch pad 900, thin
adhesive layers 910 are used to mechanically couple the beads to the rest of the touch
pad structure and the structure itself to base 665. One illustrative layout and spacing of
deformable beads 905 is shown in FIGS. 9B (lop view) and 9C (cross-section). Table 3
identifies the approximate dimensions for each component of touch pad 900 that is
different from prior illustrated touch pad 600.

Table 3: Dimensions for Illustrative Touch Pad 900

Layer

Material

905

Rubber or polymer (e.g., elastomer)

910

Pressure sensitive adhesive ("PSA") or ultraviolet

Thickness (mm)
0.015

("UV") light cured adhesive

a

Column bead separation

1.0

b

Row bead separation

1.0

c

Bead offset

0.5

d

Bead width

0.5

- 14 -

APLNDC00026399

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-007705)

Table 3: Dimensions for Illustrative Touch Pad 900
Layer ¡
e

Material

' Bead height

Thickness (mm)
0.15

Active touch pad surface: 271 mm × 69 mm
No of drive traces (620 and 650): 13
Number of sense traces (625): 54
Pixel separation: 5 mm

[0033]

Referring to FIG. 10A, in another embodiment of a combined touch and

force sensitive touch pad in accordance with the invention (touch pad 1000), spring
membrane 1005 is used instead of raised structures (e.g., 530 and 655) or
deformable beads (e.g., 805 and 905). In touch pad 1000, thin adhesive layers 1010

are used to mechanically couple PET spring 1005 to layers 635 and 640 as well as to
mechanically couple layer 645 to base 665. Referring to FIG. 10B, in one embodiment
spring membrane comprises a single rippled sheet of PET whose run-to-rise ratio (i.e.,
a/b) is typically in the range of approximately 10:1 to 50:1. One of ordinary skill in the
art will recognize that the exact value used in any given embodiment may change due
to a variety of factors such as, for example, the physical size of the touch pad surface,
the amount of weight specified for full deflection (e.g., 200 grams) and the desired
sense of "stiffness" presented to the user. Table 4 identifies the approximate
dimensions for each component of touch pad 1000 that is different from prior
illustrated touch pad 600.

- 15 -

APLNDC00026400

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

Table 4: Dimensions for Illustrative Touch Pad 1000

Layer

Material

Thickness(mm)

1005

PET

0.75

1010

Pressure sensitive adhesive ("PSA") or ultraviolet
("UV") light cured adhesive

0.025

a/b

Spring run-to-rise ratio

10:1 a 50:1

Active touch pad surface: 271 mm × 69 mm
No of drive traces (620 and 650): 13

Number of sense traces (625): 54
Pixel separation: 5 mm

[0034]

Referring to FIG. 11A, in another embodiment rippled spring membrane

1005 may be replaced by dimpled spring membrane 1105. In this implementation,

spring membrane 1105 is a single sheet of deformable material (e.g., PET) that has
dimples formed in it by, for example, thermal or vacuum forming techniques. Figures
11B and 11C show top views of two possible dimple arrangements. Two illustrative

layouts (lop view) for dimpled membrane 1105 are shown in FIGS. 11B and 11C. As
used in FIGS. 11A-11C, the "+" symbol represents a raised region and a "-" symbol
represents a depressed region. Table 5 identifies the approximate dimensions "a"
through "e" specified in FIG. 11A.

- 16 -

APLNDC00026401

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

Table 5: Dimensions for Illustrative Spring Membrane 1100
Layer
Material
Thickness(mm)
1105
a

0.075
1.0

b

Dimple width

1.25

c

Dimple separation

2.5

d

[0035]

PET
Dimple top length

Dimple rise and fall length

0.075

Various changes in the materials, components and circuit elements are

possible without departing from the scope of the following claims. For example, drive
traces and sense traces in accordance with FIGS. 1-10 have been described as being
orthogonal. The manner in which drive traces and cut across or intersect with sense
traces, however, generally depends on the coordinate system used. In a Cartesian
coordinate system, for example, sense traces are orthogonal to the driving traces
thereby forming nodes with distinct x and y coordinates. Alternatively, in a polar
coordinate system, sense traces may be concentric circles while drive traces may be
radially extending lines (or vice versa).
[0036]

In addition, in the embodiments of FIGS. 1 and 2, drive layer 135 and

drive traces 140 (and, therefore, connector 145) may be incorporated within and on
spring membrane 125. That is, drive traces 140 could be laid down or etched on a
surface of flexible membrane 125. Similarly, drive traces 535 could be incorporated into
and as part of flexible membrane 525 (see FIG. 5).

- 17 -

APLNDC00026402

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

[0037]

One of ordinary skill in the art will also recognize that beads in accordance

with FIGS. 8 and 9 (see FIGS. 8 and 9) could also be used in place of raised structures
130, 530 and 655 (see FIGS. 1, 2A, 2B, 5 and 6). Similarly, spring mechanisms 1005
(see FIG. 10) and 1105 (see FIG. 11) could be used in place of beads 805 (see FIG.

8), deformable beads 805 and 905 (see FIGS. 8 and 9) or raised structures 130, 530
and 655 (see FIGS. 1, 5 and 6).

[0038]

Referring to FIG. 12A, in another embodiment force detection in

accordance with the invention may be incorporated within a display unit rather than a
touchpad. For example, system 1200 includes processor 1205, standard input-output
("I/O") devices 1210 (e.g., keyboard, mouse, touch pad, joy stick and voice input) and
display 1215 incorporating force detection capability in accordance with the invention.
Referring to FIG. 12B, in this embodiment, display 1215 includes display element

1220, display element electronics 1225, force element 1230 and force electronics
1235. In this manner, user 1240 views display element 1220 of display 1200 through
force element 1230. By way of example, display element 1220 and electronics 125
may comprise a conventional liquid crystal display ("LCD") display. Force element 1230
may comprise a force-only sensor (e.g., similar to the embodiments of FIGS. 1 and 2)
or a force and location sensor (e.g., similar to the embodiments of FIGS. 5-11). Force
electronics 1235 may compose processing circuitry as described in FIG. 4. That is,
force electronics 1235 is capable of driving and sensing mutual capacitance signals as
described in connection with a touch pad in accordance with the invention.

- 18 -

APLNDC00026403

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

[0039]

It will be recognized by those of ordinary skill in the art that use of the

described force detection technology should, when applied to display 1215, utilize
transparent or substantially transparent drive and sense traces such as that provided by
ITO (Le., rather than copper which is opaque). Similarly, the gap between the first layer
of traces (e.g., drive traces) and a second layer of traces (e.g., sense traces) used to
detect an applied force (see discussion above) should be transparent or substantially

transparent. For example, compressible transparent spacers could be used to embody
offset raised structures 130, support structures 655, deformable beads 805, 905 or
spring membranes 1005, 1105.

-19 -

APLNDC00026404

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

Claims

1.

A force imaging touch pad, comprising:

a first layer having a first plurality of conductive traces oriented in a first
direction on a first surface thereof;
a second layer having a second plurality of conductive traces oriented in a
second direction on a first surface thereof; and
a deformable dielectric membrane juxtaposed between the first and second
layers,
wherein the first and second plurality of conductive traces are adapted to create
a capacitance image when a force is applied to the first layer, the capacitance image
indicative of an intensity of the applied force.

2.

The force imaging touch pad of claim 1, wherein the first plurality of conductive

traces and the second plurality of conductive traces are substantially orthogonal.

- 20 -

APLNDC00026405

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

3.

The force imaging touch pad of claim 1, wherein the deformable dielectric

membrane comprises:
a substantially flat membrane having a first surface oriented toward the first
layer and a second surface oriented toward the second layer;
a first plurality of raised structures coupled to the first surface of the
substantially flat membrane; and
a second plurality of raised structures coupled to the second surface of the

substantially flat membrane, wherein the second plurality of raised structures are
substantially offset from the first plurality of raised structures.

4.

The force imaging touch pad of claim 1, wherein the deformable dielectric

membrane comprises:
a substantially flat membrane; and
a plurality of deformable beads affixed to one surface of the substantially flat

membrane, wherein the deformable beads are adapted to compress when a force is
applied to the first layer toward the second layer.

5.

The force imaging touch pad of claim 1, wherein the deformable dielectric

membrane comprises one or more thermoplastic springs.

6.

The force imaging touch pad of claim 1, wherein the deformable dielectric

membrane comprises a dimpled deformable membrane.
- 21 -

APLNDC00026406

Application Serial No. 11/278,080 filed on 03/30/2006
Dume i NO: P3764US1
(119-0077US)

7.

The force imaging touch pad of claim 5, wherein the thermoplastic springs

comprise Polyethylene terephthalate.

8.

The force imaging touch pad of claim 1, further comprising a mutual capacitance

measurement circuit electrically coupled to the first and second plurality of conductive
traces.

- 22 -

APLNDC00026407

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

9.

A force and location imaging touch pad, comprising:
a first layer having a first plurality of conductive traces oriented in a first

direction on a first surface thereof and a second plurality of conductive traces oriented
in a second direction on a second surface thereof;
a second layer having a third plurality of conductive traces oriented in
substantially the first direction;
a base layer;
a first deformable membrane juxtaposed between the first and second layers;
and

a second deformable membrane juxtaposed between the second layer and the
base layer,
wherein the first and second plurality of conductive traces are adapted to create
a first capacitance image when one or more objects come into close proximity to the
first surface, the first capacitance image indicative of where the one or more objects are
located relative to the first surface,
wherein the second and third plurality of conductive traces are adapted to create
a second capacitance image when a force is applied to the first layer, the second
capacitance image indicative of an intensity of the applied force.

10.

The force and location imaging touch pad of claim 9, wherein the first layer

comprises a flexible circuit board.

- 23 -

APLNDC00026408

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

11.

The force and location imaging touch pad of claim 9, wherein the first layer

comprises one or more layers of thermoplastic resin.

12.

The force and location imaging touch pad of claim 9, wherein the first plurality of

conductive traces and the second plurality of conductive traces are substantially
orthogonal.

13.

The force and location imaging touch pad of claim 9, wherein the second layer

comprises a flexible circuit board.

14.

The force and location imaging touch pad of claim 9, wherein the second layer

comprises one or more layers of thermoplastic resin.

15.

The force and location imaging touch pad of claim 9, wherein the first

deformable membrane comprises a first plurality of raised structures, the second
deformable membrane comprises a second plurality of raised structures and the first
and second raised structures are substantially spatially offset from one another.

16.

The force and location imaging touch pad of claim 15, wherein the first and

second plurality of raised structures comprise thermoplastic resin.

- 24 -

APLNDC00026409

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

17.

The force and location imaging touch pad of claim 9, wherein the first

deformable membrane comprises a first plurality deformable beads, the second
deformable membrane comprises a second plurality of deformable beads and the first
and second plurality of deformable beads are substantially spatially offset from one
another.

18.

The force and location imaging touch pad of claim 17, wherein the deformable

beads comprise elastomer beads.

19.

The force and location imaging touch pad of claim 9, wherein each of the first

and second plurality of raised structures comprise one or more thermoplastic springs.

20.

The force and location imaging touch pad of claim 19, wherein the thermoplastic

springs comprise Polyethylene terephthalate.

21.

The force and location imaging touch pad of claim 9, further comprising a mutual

capacitance measurement circuit electrically coupled to the first, second and third
plurality of conductive traces.

- 25 -

APLNDC00026410

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

22.

A force and location imaging touch pad, comprising:

a first surface having a first plurality of conductive traces oriented in a first

direction;
a second surface having a second plurality of conductive traces oriented in a
second direction, the first and second surfaces juxtaposed to and electrically isolated

from one another;
a third surface having a third plurality of conductive traces oriented in
substantially the first direction; and
a deformable membrane between the second and third layers,
wherein the first and second plurality of conductive traces are adapted to create
a first capacitance image when one or more objects come into close proximity to the
first surface, the first capacitance image indicative of where the one or more objects are
located relative to the first surface,
wherein the second and third plurality of conductive traces are adapted to create
a second capacitance image when a force is applied to the first surface, the second
capacitance image indicative of an intensity of the applied force.

23.

The force and location imaging touch pad of claim 22, wherein the first and

second surfaces are surfaces of a common layer.

24.

The force and location imaging touch pad of claim 23, wherein the common layer

comprises a flexible circuit board.
- 26 -

APLNDC00026411

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

25.

The force and location imaging touch pad of claim 23, wherein the common layer

comprises one or more layers of thermoplastic resin.

26.

The force and location imaging touch pad of claim 22, wherein the first plurality

of conductive traces and the second plurality of conductive traces are substantially
orthogonal.

27.

The force and location imaging touch pad of claim 22, wherein the third surface

comprises thermoplastic resin.

28.

The force and location imaging touch pad of claim 22, wherein the deformable

membrane comprises:
a substantially flat membrane having a first surface oriented toward the first
plurality of conductive traces and a second surface oriented toward the third plurality of

conductive traces;
a first plurality of raised structures coupled to the first surface of the
substantially flat membrane; and
a second plurality of raised structures coupled to the second surface of the
substantially flat membrane, wherein the second plurality of raised structures are
substantially spatially offset from the first plurality of raised structures.

- 27 -

APLNDC00026412

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

29.

The force and location imaging touch pad of claim 22, wherein the deformable

membrane comprises:
a substantially flat membrane; and
a plurality of deformable beads affixed to one surface of the substantially flat
membrane, wherein the deformable beads are adapted to compress when a force is
applied to the first layer toward the second layer.

30.

The force and location imaging touch pad of claim 22, wherein the deformable

membrane comprises a dimpled deformable membrane.

31.

The force and location imaging touch pad of claim 29, wherein the deformable

beads comprise polymer.

32.

The force and location imaging touch pad of claim 22, wherein the deformable

membrane comprises one or more thermoplastic springs.

33.

The force and location imaging touch pad of claim 32, wherein the thermoplastic

springs comprise Polyethylene terephthalate.

34.

The force and location imaging touch pad of claim 22, further comprising a

mutual capacitance measurement circuit electrically coupled to the first, second and
third plurality of conductive traces.
- 28 -

APLNDC00026413

Application Serial No. 11/278,080 filed on 03/30/2006
DOCKET NO: P3764US1
(119-0077US)

35.

An electronic device, comprising:
a pm-sing unit;
a display unit operatively coupled to the processing unit;
a mutual capacitance measurement circuit operatively coupled to the processing

unit; and
a force and location imaging touch pad in accordance with one of claims 9 and
22 and operatively coupled to the mutual capacitance measurement circuit.

36.

The electronic device of claim 35, wherein the electronic device comprises a

computer system.

37.

The electronic device of claim 35, wherein the electronic device comprises a

mobile telephone.

38.

The electronic device of claim 35, wherein the electronic device comprises a

personal digital assistant.

- 29 -

APLNDC00026414