Touch Screens for LCD Monitors
Capacitive, Resistive, SAW, Infrared, and Other Touch Technologies
It’s well known that keyboards, mice and other pointing
devices are impractical in certain environments. They are fragile, vulnerable
to abuse, susceptible to liquid and dust contamination, and contribute
to repetitive-motion injuries.
Touch screens offer ease of use, speed, accuracy, and
negate the need to become proficient with a handheld device. General
the option of equipping your LCD monitor with a variety of touch technologies,
In 1977, we created the world’s first touch responsive
industrial terminal, the VuePoint™.
have a true touch screen; rather, the VuePoint was equipped with a circuit
board onto which infrared LEDs were mounted. The LEDs were arranged to
form a 12 x 40 grid and when the screen was touched, the infrared beams
were broken, indicating the touch location to the terminal. Thus, an
operator could control a system right at the terminal.
As touch screen technology evolved (along with monitor
technology), we incorporated various touch panels into our LCD monitors,
starting with our SlimLine series
of flip-up LCD monitors. Over time and based on demand, our Saber RackMount,
PanelMount and Standalone Series became the next logical candidates for
touch integration. This was due to increased use of flat panel technology
in human-machine interface applications.
Today, we offer several types of touch technology
on all but a few of our LCD monitors.
Resistive Touch Screens
Though it’s continually improved upon, the technology that goes
into resistive touch screens goes back many years, making it the “tried-and-true”
and economic choice. They feature a glass panel with a uniform resistive
coating, and a
thick polyester conductive (on one side) coversheet separated by small,
transparent insulating dots. When the screen is pressed with a finger
or stylus, the conductive
coating makes electrical contact with the coating on the glass, thus
registering a touch. Resistive touch screens are extremely resilient
to wear and tear, making them a good choice for high-traffic applications.
SAW Touch Screens
Featuring pure glass construction, Surface Acoustic Wave (SAW) touch screens
will almost never physically “wear out” due to a superior scratch-resistant
coating. Excellent light transmission ensures that the image clarity
of the display remains sharp and vibrant. The stable, “drift-free” operation
means that the touch response is always accurate. They work well with
a finger, gloved hand, or a soft stylus. And SAW touch screens have a
sensitive touch response—they recognize the touch location and the amount
of pressure applied.
Surface Capacitive Touch Screens
Being an all-glass design, light transmission of surface capacitive
touch screens is improved, when compared to resistive touch screens.
This improves display viewability and reduces eye fatigue. Featuring
a scratch-resistant top coat, durability in heavy-use environments is
easily maintained. This type of touch screen is ideally suited for rugged
industrial or military applications.
Projected Capacitive Touch Screens
Designed for “full multi-touch” capabilities, this touch screen
technology goes beyond the traditional zoom, pinch, expand and rotate functionality,
offering an interactive tool of 20 resolvable touches at less than 6
millisecond (ms) point speed. That kind of responsiveness overcomes latency
issues associated with software filtering factors and/or slow touch response
rate. The anti-stiction glass surface enhances simple and advanced gestures,
even with nitrile, latex or vinyl gloves. With over 3300 touch sensing
points, optimal precision and accuracy are just “business as usual.”
Infrared Touch Screens
Infrared touch technology doesn’t rely on an overlay or a substrate to
register a touch, so there it cannot physically “wear out,” thus ensuring
a long product life cycle. Possessing superior optical performance and
excellent gasket-sealing properties, an infrared touch screen is ideal
for harsh industrial environments and outdoor kiosks. They work with
a finger, gloved hand, stylus, and most any object wider than 1/10".
They adjust to changing light conditions, even direct sunlight. And they
benefit from stable, no-drift calibration performance.
Optical Touch Screens
Working in tandem, two optical sensors track the movement of an object
close to the surface by detecting the interruption of the touch screen’s
infrared light source, which is emitted in a plane across
the display surface and can be either active (infrared
LED) or passive (special reflective surfaces).
Optical touch screens use a controller board
that receives signals from the optical sensors,
then compensates for optical distortions and triangulates the position
of the touching object with extreme accuracy.
The infrared light source and
optical sensors of the touch screen are synchronized using a sophisticated
algorithm that also reduces the effect of ambient light, thus creating
a very clear, accurate touch selection.
Dispersive Signal Touch (DST) Technology
Developed specifically for interactive digital signage applications, Dispersive
Signal Technology determines a touch point by measuring the mechanical
energy (bending waves) within a substrate created by the pressure of
a finger or stylus. As these bending waves radiate away from the touch
location, the signal spreads out over time due to the phenomena of dispersion.
The “smeared” signals are then interpreted by a complex set of algortihms
to precisely pinpoint the exact touch location on the screen.
DST is a passive technology, waiting for a signal created
by a touch impact. Therefore, contaminants such as dirt, grease, and
other solids can accumulate on the surface and edges of the display screen
without significantly affecting touch responsiveness. In addition, surface
damage such as scratches has no significant impact on touch performance.
The sophisticated and optimized controller that continuously
monitors for a touch impact is the fastest and most responsive technology
available for large format displays, offering greater than 99% touch
General Digital is an authorized DST integrator. Our
engineers possess the expertise to seamlessly integrate DST technology
into your large format monitor, ensuring a reliable interaction with
“Which technology is right for me?”
General Digital’s Sale Engineers are quite knowledgeable at determining
what will best suit your particular application. Contact
us at 800.952.2535 today
and we will be happy to take the time to understand your needs and
make our recommendations.