Philips Semiconductors
Product specification
Advanced modem/audio analog front-end
UCB1200
PLATE RESISTANCE MEASUREMENT
The plate resistance of a touch screen varies typically a lot due to processing spread. Knowing the actual plate resistance
makes it possible to compensate for the plate resistance effects in pressure resistance measurements. The plate
resistance decreases when two or more spots on the touch screen are pressed. In that case a part of one plate, e.g. the
X plate is shorted by the other plate, which decreases the actual plate resistance
Vtscbias
iplate
tspx
tsmy
tspy
tsmx
Fig.10 Touch screen setup for plate resistance.
The plate resistance measurement is executed in the same way as the pressure resistance measurement. In this case
only one of the two plates is biased and the other plate is kept floating. The current through the connected plate is again
a direct indication of the connected resistance.
1998 Jul 22
15
NXP [ NXP ]
