Hover Signal-Profile Detection

The touch screen market continues to develop rapidly, capturing an increasing variety of applications. One of the more advanced features that can improve user-friendly interaction is Hover technology. This means a finger position can be determined while approaching, but not yet touching, the touchscreen or touchpad.An approaching finger can be detected using different physical principles. Currently, the most common are infrared, optical, magnetic, and capacitive sensors.Cypress Semiconductor uses capacitive sensors to detect Hover. The advantage of this technology is that a capacitive Hover solution is largely compatible with standard multi-finger touch technology, if the sense-electronics can detect these extremely small Hover signals.The use of Hover technology in automotive touchscreens, for example, can increase operational safety. This allows the driver to perform certain operations (such as changing the volume of the radio, or making/rejecting phone calls) with a simple gesture instead of reaching to the touchscreen for a specific button and thus distracting from the situation on the road.The challenge is to develop algorithms that provide stable finger detection across the touchscreen where the signal-to-noise ratio is extremely unfavorable.

I. Introduction

The main challenge presented by touchscreen Hover is much smaller changes of capacitance from the hovering finger compared to signals when a finger touches a touch panel - at the same levels of internal and external noise.