Device Description MV4-150-TA1, MV4-450-TA1, MV4-170-TA1, MV4-470-TA1 1-22
Moeller 07/01 AWB-C2700-1347GB
13 Touch Screen
13.1 Basic Touch Screen function
The Touch Screen operates on the active light matrix principle in the infrared range. The optical elements of
the light matrix are located behind the IR transparent plastic frame in the front panel of the device. They are
located in such a way that their radiation extends slightly out of the front pane. Each emitter is assigned a
receiver that is located on the other side. In this way 40 closely positioned IR channels are provided on the
5.7″ unit and 70 IR channels on the 10.4″ unit (see Section 17). A touch on the screen is detected by the
simultaneous interruption of one or several channels in the X or Y axis.
Repeated touches and touches that cover an area greater than 20 mm x 20 mm are not evaluated by the
controller. Continuously interrupted channels caused by severe contamination and dirt, or by the failure of an
optical element are detected by the touch controller and are no longer included in the evaluation.
13.2 Power up function test
The Touch Operator Panel carries out a function test of the touch screen with each power up of the device.
This test measures the signal levels of all IR channels and compares them with initial values. The initial
values are determined before the device is delivered and stored in a retentive memory.
If the signal of one or several channels is below a minimum level relative to the initial values, this will be
indicated by an error message on the screen and the
DEF/DIRTY
LED (see Section 12). A reduced signal level
of this kind is normally due to severe contamination of the IR transparent plastic frame which consequently
has to be cleaned (see Section 13.3). The Touch Screen, however, remains fully functional.
Only an increase in the contamination of the screen will lead to the continuous interruption of one or several
IR channels. IR channels that are continuously interrupted will be detected by the Touch Controller and no
longer included in the evaluation. In extreme cases, this may mean that individual zones cannot be activated
by touch.
Do not touch the screen whilst the system is being started up, and wait tillyour
application has started.
During the startup the Touch Screen carries out a function test in which the signal
levels of the IR channels are measured.
13.3 Cleaning and maintenance of the Touch Screen
For operation ensure that the signal levels of the channels are not so severely reduced or interrupted due to
excessive contamination through dirt (see Section 13.1).
Clean the inside of the plastic frame of the device regularly (see Section 15) with a damp soft cloth. Ensure
that the surface is not scratched or scoured, especially when removing hard deposits and abrasive dust.
Do not expose the front of the device to solvents which may corrode and destroy the plastic frame (frame
material: polymethylmethacrylate, PMMA).
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