VX121P/151P/171P(-QM57)
User’s manual rev.0.0 (Preliminary)
54 of 68
MU-C656.xxxxxxxxxx r.0.0-EN
8.20 Touchscreen
The touchscreen is an order option.
Characteristics
Type:
8-wire analog resistive with antiglare surface
Light transmission:
80% (typ.)
Surface pencil Hardness:
3H (ASTM-D-3363-92A)
Controller:
TSHARC 12bit (RS232 serial interface 9600 baud to
COM4).
Functional description
The analog resistive touchscreen is a sensor consisting of two opposing layers,
each coated with a transparent resistive material, separated by a pattern of very
small transparent insulating dots. Touching the top surface compresses the
flexible top layer to the supported bottom layer causing electrical contact of the
two layers between the span of insulating dots. Determining a touch location
requires two measurements, one to obtain an X-axis coordinate and one to obtain
a Y-axis coordinate. Applying a drive voltage across one layer produces a voltage
on the other layer that can measured using an A/D (Analog to Digital) converter.
The touchscreen interface is made by a dedicated microcontroller. Touch point
coordinates are reported to the Motherboard through the serial communication
port (COM). The A/D converter used is a 12-bit type that can resolve up to 4096
different input values in each the horizontal and vertical direction. The analog
resistive touchscreen used in the Panel PC is 8-wire type. This design
compensates for resistance changes inherent to any touch system. Resistance
changes are caused by ageing, use, temperature, and humidity.
The layers of the touchscreen are laminated to a chemically strengthened glass
backing panel. The backing panel gives the layers rigidity and protects the display
used behind the touchscreen.
The layers are made of polyester (PET) with the external side coated with an
abrasion and chemical resistant anti-glare hard coat.
Use and care
The touchscreen assembled on the Panel PC is useful for use with fingers,
gloves, pen tip, or other pointing device with rounded edge.
Caution
Avoid pressing the touchscreen with sharp pointing device.
Permanent damage to the touchscreen can occur.
