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Touch-Sensing Input Devices

Ken HinckleyMike SinclairMicrosoft Research

CHI’99 Conf. on Human Factors in Computing Systems

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What is Touch-Sensing?

Input modality for sensing contact of the bare hand or fingers

Touchpads, touchscreens, touch tablets Touch, Release events touching & positioning tightly coupled…

Ignored by most software & other devicesTechnology is cheap, simple, no calibration

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Why Do This?

Changing hardware changes all the rules!

Sensing enables new UI’s with better awareness of context and thus can potentially both simplify & enhance the user experience.

Extend to desktop devices / computing Both implicit & explicit usage

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Some Examples of Sensing for UI

Buxton: “Proximal Sensing”Harrison et al., handedness detect on

PDASliders on mixing consolesZimmerman et al: Electric field

sensing Cameras, Sinks in public restrooms, ...

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Some Examples of Sensing for UI

Buxton: “Proximal Sensing”Harrison et al., handedness detect on

PDABuxton: touch-sensitive treadmillsZimmerman et al: Electric field

sensing Cameras, Sinks in public restrooms, ...

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The Touch Mouse

Sense contact from user’s hand via capacitance

New events: Touch, ReleaseWhat is sensed what the user feels

Emulation from software... Did user release mouse? Or just holding

still? Cannot emulate multiple sensors at all.

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How the Touch Mouse Works

Your body is a capacitor

Square waveon surface

Hand causestime delay

t

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What’s a Touch Mouse Good For?

Allocate screen real estate more intelligently Tension: UI always up vs. max doc real estate Most widgets only useful if you’re holding mouse So fade in / out portions of display via touch!

No retraining necessaryVIDEO

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Fading out Toolbars

Fading chosen as minimally distracting animation

Asymmetric: .3s fade in 1s fade-

out

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Interaction Style vs. Display-Only Style

Some GUI elements provide visual feedbackThese can fade to compact representation

when user isn’t holding the mouse1

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Cursor Feedback

Cursor “sonar” on touch draws attention to locus of interaction

Hide cursor on release

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Usability Testing Results

Informal usability study with 11 usersTest users loved it: Easy and it just does

the right thing “I like that the toolbar comes up quickly when

you need it… and all the extra stuff isn’t there when you don’t need it.”

Also tried leaving toolbar semi-transparent “It looks like a wet newspaper.”

Planning more formal experiment

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Feedback for Toolbars...

Users dislike transparent toolbar.

But it gives useful feedback...

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Another Example: Explicit Interaction

Explicit usage: intentional gesturesfor Enhanced scrolling Tapping above/below wheel for Page Up/Down Roll-and-hold for continuous autoscrolling Reading sensor: Dwell time on wheel (?) Tapping tested very well: paging 4.6 out of 5 Doesn’t interfere with normal use of wheel

Tap-and-hold? Tapping, then resting, is not possible

Same controls more useful on keyboard?

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What Are Some General Properties of Touch-Sensing?

What are touch-sensing devices good for?

What are some of the design trade-offs involved?

Our answers so far based on practice & experience, no formal experiments yet.

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Intentional Control vs. Cognitive & Physical BurdenButton-click Touch Hand-near-devicePotential problems?

Decrease in user’s intentional control Increase in SW inferential burden (error rates)

Use these “problems” to our advantage! Decreased cognitive burden to make decisions Touching is something the user must do anyway

Provide useful services with a low cost from errors of intent / interpretation.

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Some Important Properties of Touch-Sensing Devices

Zero activation force: “accidental” activation. prone to inadvertent contact for explicit actions

Flexible form factor: It’s paint! curved surfaces, tight spaces, moving parts, …

Unobtrusive: near zero vertical profile.

Deactivation from software can ignore inputs without giving false “click”

feedback

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Conclusions

When matched to appropriate interaction techniques, the unique properties of touch-sensing devices allow user interfaces to effectively support new behaviors. users find our techniques compelling and

usefulExample of applying sensing technolgies

to benefit user interactionPromising area that needs more work.

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Classification of Tactile Input Technologies

Contact type Discrete/ Continuous Single/Multiple

inputs

Limitations... Technology-centric Only some sensors Doesn’t distinguish

technologies w/in cell Ignores position /

orientation sensing

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Traditional Input Devices with Touch

Buxton input taxonomy: devices operated by touch vs. mechanical intermediary

Touchpads, touchscreens, touch tablets cannot position without touching nor touch without positioning…

Buxton, Hill, & Rowley: touch-tablets senses Touch, Release events; a mouse cannot

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Similarities to Touch Tablets

One can potentially confer some desirable properties of touch tablets to the mouse.

Buxton, Hill, & Rowley 1985No moving parts for touch sensors.No mechanical intermediary -- use bare hand.Operation by feel: Tactile cues can correspond to

touch-sensitive regions.Amount & type of feedback. No “click” of a

button. May be undesirable for implicit interactions anyway.

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Example Circuit

Pad(conductive paint)

330k

0.1F74HC74

GND

VCC

MOUSE_GND

MOUSE_POWER

74HC74

SetD

Clk

Clr

dx,d

x,y

dx

Q’1m

0.1F74HC74

GND

dx,dy

74HC14

To parallel port

pin 15 (S3)

x,ydx

74HC140.33F74HC74

GND

To parallel port

pin 18-25 (Gnd)

GND

30Hz

100k

Q

Very simple! For 1 sensorneed to sync

multiple sensors

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Why Sense Touch?

Touch is important human sensory channel contact with objects, pets, people

What is sensed what the user feelsIgnored by most input devices &

softwareTechnology is cheap, simple, no

calibration= Opportunity!

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TouchTrackball for ToolGlass Interactions

ToolGlass fades in when user touches trackball Toolbars also fade out if they are visible Release trackball Reverts to toolbars (if holding

mouse) or clean screen if not.