Enlisting semiconductor sultan AMI Semiconductor,
Tyco Electronics’ Acoustic Pulse
Recognition (APR) touch technology may
be appearing on a cell phone near you soon.
AMI has agreed to develop a silicon solution that will allow the
integration of APR touch technology from Tyco’s Elo Touch-
Systems group with handheld and mobile devices.
Normally associated with larger touchscreen installations
in the commercial and industrial spaces, the APR technology
may soon find a home in portable consumer products like cell
phones, PDAs, navigation units, portable gaming, and signature
capture, as well as in handheld industrial and medical
devices. According to Ken North, director of engineering at
Elo, the partnership will extend the boundaries in which APR
technologies operate (Fig. 1).
HOW APR WORKS
APR combines the features of existing touch technologies
within a single package while offering an alternative to capacitive
and resistive topologies. A basic implementation consists
of a display with a glass overlay and a small USB control board
(Fig. 2). An audio-based technology, APR recognizes the
sound created when the glass is touched at a preset position,
which can vary depending on the application.
This audio approach enables touch input via finger, fingernail,
gloved hand, or stylus. The technology also includes palm rejection
functionality. The screen is scaleable in size from that of a
PDA up to a 42-in. diagonal. The glass overlay offers durability
in its resistance to liquids and other contaminants, including
chemicals that do not affect glass such as acetone, toluene, methyl
ethyl ketone, isopropyl alcohol, methyl alcohol, ethyl acetate,
ammonia-based glass cleaners, gasoline, kerosene, and vinegar.
APR touch activation force is in the realm of 55 to 85 g with
a maximum positional accuracy of 1%. Touch-point density
depends on a controller resolution of 4096 by 4096 with a light
transmission figure of 92% ±2%. Operating temperature ranges
from –20°C to 60°C, with a storage temperature range from
–40°C to 71°C. Other environmental operating limits include
a relative humidity of 90% maximum at a maximum of 50°C
for 240 hours non-condensing and a maximum operating altitude
of 3048 m. Its storage and transport limit is 15,240 m.
The technology provides electrostatic-discharge protection
as per EN 61000-4-2, 1995 and meets Level 4 based on
15-kV air and 8-kV contact discharges. It also carries UL, cUL,
TUV, CE, and FCC Class A approvals and is sealable to meet
NEMA 4 and 12 and IP 65 standards.
APR’s surface durability, specified as that of pure glass, offers
a hardness rating of 7. As the technology relies on no moving
parts, coatings, or layers, life expectancy exceeds 50 million
touches in a single location using either a finger or stylus. For
certain applications, impact resistance can meet UL-60950
and CSA 22.2 No. 60950 ball-drop test requirements, which
entails dropping a 0.5-kg/50-mm diameter ball from a height
of 1.3 m on the design.
THE SEMICONDUCTOR CHALLENGE
APR technology is native to PDA-size and larger touchscreens,
but not the tiny displays common to cell phones and other
palm-sized electronics. It also relies on recognizing the audible
characteristics of touching the screen in whatever manner.
Considering how and where most consumers use cell phones
and other devices, grooming an audio chip that will reliably
allow accurate, uninterruptible input with instant user gratification
is a formidable task. Also, smaller screens increase the
chance for proximity errors since the closeness of preset input
points is extremely high.
AMI Semiconductor has some difficult work ahead. The company
isn’t giving up much information on this proprietary project
for now, but as the year progresses, we’ll follow up on the results
of those labors. “The development of an APR IC has the potential
to enable Kanji writing and to scale screen size more effectively
than other touch technologies, potentially accommodating
displays from 1.8 in. to over 65 in.,” North said. We shall see.