Non-finger detection, baseline removal, and power adapters
This topic provides notes for multi-touch hardware solutions on non-finger detection, baseline removal, and power adapters.
A non-finger is defined as a component that is likely not a finger due to its size and shape, as well as the distribution of its sensor pixel values.
A non-finger can be detected through certain approaches. A simple approach is to use a certain set of heuristic tests such as area test, shape test, fractional dimension test, and so on.
Non-finger detection can also be used to report the touch as palm with the palm indicator set.
Massive interference with all scenarios – causes non-fingers to be interpreted as finger touches.
Baseline removal – failure to identify a non-finger can lose the chance to promptly update the baseline, resulting in sub-optimal balance between the sensitivity and ghost reports.
Properly and promptly identify the baseline case within a short time that such updating will not interfere with user attention of baseline change and remove it immediately.
- Sub-optimal balance of sensitivity and ghost reports.
Different power adapters can generate different noise levels that impact touch performance. Each unique power adaptor configuration should be considered as a unique touch device. Thus if the same touch device is shipped with two different power modules (for example, 2 pins or 3 pins for different regions), each should be considered as a unique touch device.