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Section
4
4.1
Touch Screen Introduction
Touch screen interfaces have become the standard interface in the past 5 years. They are,
rugged, reliable, extremely flexible and easier than ever to implement! Over 90% of the
display packages Vartech Systems builds are touch screen systems. If you are uncertain
about using a touch screen, or are having difficulty, please call us. The universal acceptance
of the Windows GUI [Graphical User Interface] along with the extensive use of a mouse
interface has significantly accelerated the use of touch interface. Basically think of your touch
screen as if it were a mouse.
Touch Screen Definition
4.2
Quite simply, Vartech Systems touch systems are a mouse emulator. By installing a software
driver and connecting to a serial port, the touch screen will support all the primary mouse
functions:
Our standard touch screen interface, is a high resolution analog resistive. Following is a quick
explanation of what all this means.
High Resolution: The touch screen resolution is 400 ppi [points per inch]
Analog Resistive: The actual touch glass is an analog device. Meaning there is a very low
voltage applied to the X and Y axis of the touch screen. This current is applied to ITO [Iridium
Tin Oxide] that is sputtered onto a polyester membrane. When you touch the screen you are
changing the resistance on both the X and Y axis, producing an analog value that references
a particular location.
This type of screen can be activated with a gloved finger or mechanical stylus.
The touch screen itself is connected to electronics that provide the Analog to Digital
conversion. When the screen is touched, the electronics convert the analog voltage to a
digital value and add a "Mouse Click", then sends the data to the serial port that the driver is
loaded to. When the touch is released the new XY location is sent along with a "Mouse Up
Click".
This system requires no special software knowledge, and can be installed and set up in
minutes. The following section gives a detailed explanation of the software setup and
configuration.
Since the touch screen interface is RS-232, the recommend maximum distance from the PC
is 50 feet. In reality, every application is different. The touch driver default baud rate is 9600,
and we have tested the driver and interface with good quality cables to 50 feet. With RS-232
line drivers this can be extended almost indefinitely.
17.0" PowerVue User Guide
17
TOUCH SCREEN
150-059
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