Hardware Reference
In-Depth Information
There are several technologies used for multitouch sensitive touchscreens, including the following:
•
Capacitive
—A transparent conductive matrix creates a grid of capacitors. When a finger or
conductive stylus is close to the surface, the grid sees a change in capacitance at a specific
location on the screen.
•
Resistive
—Transparent conductive and resistive coatings create a grid of tiny switches, which
can detect the press of a finger or stylus at a specific location on the screen.
•
Optical
—Retro-reflective optical sensors in groups of pixels on the screen detect the shadow
of a finger or stylus at a specific location on the screen.
While each of these technologies has various advantages and disadvantages, the most popular
technology for multitouch displays is Capacitive. In the end the specific technology is mostly
transparent to the user. It simply works.
The display portion of a monitor with a multi-touch sensor attaches to the PC like any other display—
that is, via a DVI, HDMI, DisplayPort, or possibly even an analog VGA connection. The touch sensor
attaches via a separate USB cable, and most of these displays also include a built-in USB hub
allowing additional USB devices to be attached to the display.
Using a display with multi-touch capability is a no-brainer where tablets are concerned, but for
laptop and especially desktop PC use, the jury is still out. I, for one, am insistent on having a display
that is absolutely clean and free of fingerprints, smudges, or other debris. The idea of fingering up the
displays on either my laptop or desktop systems is abhorrent. In addition, most, if not all, of the
screens available with multitouch capability are glossy, which is a deal-breaker for me. Because I
want to see what is on the display (and not what is behind or above me) I insist on anti-glare or matte
displays for both laptop and desktop systems. Touchscreen technology is not dependent on having a
glossy screen, but since it is a consumer-oriented technology, and all consumer-oriented displays are
glossy, it seems you are forced to have one with the other.
Then there is the cost. Because multitouch desktop and even laptop displays are fairly new with the
advent of Windows 8, they are currently several times more expensive than those having the same
size and resolution without a multitouch sensor. It remains to be seen how popular these types of
displays will become in the future for normal desktop or even laptop PC use.
Wireless Input Devices
For several years, many manufacturers have offered wireless versions of mice and keyboards. In most
cases, these devices have used either IR or short-range radio transceivers to attach to standard USB
or PS/2 ports, with matching transceivers located inside the mouse or keyboard. Wireless input
devices are designed to be easier to use in cramped home-office environments and where a large-
screen TV/monitor device is used for home entertainment and computing.
Many manufacturers, including Microsoft, Logitech, and second-tier vendors, offer bundled kits that
include a wireless keyboard and mouse that share a transceiver. Because many of these keyboards
and mice have the latest features, including programmable keys, multimedia and Internet-access keys,
and optical sensors, these wireless combos are often the top-of-the-line products from a given vendor
and are often less expensive than buying the keyboard and mouse separately.
The three major technologies used by wireless input devices are as follows:
• IR
