Device description GF0
MICRO PANEL
Touch Screen
26
Technical subject to change
M000235-01.DOC
© by Micro Innovation
13 T
OUCH
S
CREEN
13.1 P
RINZIPIELLE
F
UNKTION DES
T
OUCH
-S
CREEN
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 (
→
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 P
OWER UP FUNCTION TEST
The GF0 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 (
→
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 (
→
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 C
LEANING AND MAINTENANCE OF THE
T
OUCH
S
CREEN
For operation ensure that the signal levels of the channels are not so severely reduced or interrupted
due to excessive contamination through dirt (
→
Section 13.1).
Clean the inside of the plastic frame of the device regularly (
→
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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