UM10720 Datasheet, PDF (12/16 Pages) NXP Semiconductors – User manual for the TFT touch demo board OM11058

NXP Semiconductors
UM10720
User manual for the TFT touch demo board OM11058
4. Waterproof touch display with ultra fast auto-calibration
• A liquid droplet or thick film of condensation is continuously compensated. (See
http://www.youtube.com/watch?v=K7RZM8fPVlw).
• A significant water droplet or a water splash creating a film of water over a touch
display or a capacitive touch control panel results in increased capacitance. However
the self-capacitance measurement technique is the most efficient way of
adaptability.‘(See http://www.youtube.com/watch?v=CT6acNtj-5c).
• Another mechanism for capacitance change could be a magnetic or piezoelectric
haptic feedback generator changing the input capacitance to different levels after
every event as well as mechanical deformations. This is also automatically
compensated.
4.1 Ensuring reliable operation
• Regardless of what causes a capacitive event, the most important action is to bring
the capacitive sensor back to a functional state after every event: be it a real touch, a
water droplet, a haptic feedback event or a mechanical movement.
• Fast auto-calibration after every touch and action ensures that the sensor is always
ready for the next touch (fast auto-calibration runs 50 times faster than normal
auto-calibration). This procedure takes just a few milliseconds (1 ms to 5 ms) and the
sensor IC enters operation mode as soon as the fast calibration is completed, without
any further intervention from the microcontroller.
UM10720
User manual
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 25 June 2013
© NXP B.V. 2013. All rights reserved.
12 of 16