Probably the greatest demand for highly featureridden
touchscreens comes from the portable
market, with the iPhone and similar communications
products as ripe examples. But
while it’s one thing to integrate a simple touchscreen accepting
single-touch input to control the basic functions of a device,
simple touchscreens are few and far between these days.
Give or take a few millimeters, the typical area for input on
a cell phone is about the size of a credit card, which is barely
enough room for an average finger to maneuver. In addition to
basic numeric input for phone dialing, the touchscreen designer
needs to squeeze into this space a plethora of other functions
that often need to operate simultaneously, like cameras, address
books and calendars, Internet and e-mail activities, video,
music, and texting, with more yet to come.
As if shrinking space and expanding functionality weren’t big
enough challenges, the manner in which end users address the
touchscreen goes way beyond a single tap of the finger. Various
gestures, i.e., sweeping, scrolling, rocking, variable pressure, and
even shaking, are now the norm. The input area must be able
to recognize each novel input type, associate it with the desired
function, and enable the execution of that function accurately
every time.
Naturally, this critical responsibility rests primarily on the
shoulders of the touchscreen sensor. Synaptics says it has these
concerns under control with its ClearPad sensors. According
to the company, these high-resolution capacitive components
for cellular phones, smart remote controls, digital cameras, and
other devices provide an easy-to-use, discoverable interface for
screen navigation, selection, and interactive input.
CLEARPAD BASICS
Custom designed for fit, a ClearPad sensor lays over the
LCD providing the GUI. The sensor supplies the touch-activated
interface buttons and controls (see the figure). Supporting
design flexibility, the size and placement of the GUI controls
can vary, accommodating a specific application or user mode.
RoHS-compliant with additional green-manufacturing
options available, the sensors’ size and shape are customizable.
Sensitivity is tunable for operation under a casing or plastic
coversheet measuring up to 1.2 mm thick. Touch panels can
be designed with a glass or polyethylene-terephtalate (PET)
substrate. The sensors also save power via doze, sleep, and
deep-sleep modes and are ready for use in as little as 100 ms
from device power-up.
Unlike resistive topologies, the capacitive components don’t
create wells or valleys around the sensor, enabling a smooth
appearance. ClearPad sensors also promise to minimize internal
reflections and specify resolutions beyond 500 dpi. They don’t require calibration, and they don’t have any moving parts.
And, they’re highly resistant to contaminants and moisture.
DOING THE HAND JIVE
One of the sensors’ most notable features is their ability to
recognize and accurately translate gestures, or the manner in
which users interface with the touchscreen. Functions relevant
to a particular gesture are customizable for a specific device or
application, and the sensors support a wide variety of gestures
for enhancing usability.
These gestures include flicking to scroll through photos and
lists, two-finger pinching to zoom in and out, finger presses to
display information, taps to launch or close an application, taps
and slides to move files or icons, and double taps to activate
other functions. Since all of these inputs are customizable,
they’re just a few examples of what a particular gesture can
activate within a particular device.
ClearPad sensors are gaining significant ground in the market
as well. For example, NTT DOCOMO/Sharp’s SH906i
clamshell handset debuted in June as the first ClearPadenabled
touchscreen in Japan’s mobile handset market.
In addition to gestures, the handset employs ClearPad technology
to enable finger-input character recognition capabilities
for Japanese character entry. According to Synaptics, the combination
of the SH906i’s character recognition software and its
ClearPad technology will pave the way for greater usability in
regions with even more complex alphabets.
SYNAPTICS
www.synaptics.com/solutions/products/clearpad