Elimination of environmental interference to a capacitive touch pad by a dummy trace
AssigneeElan Microelectronics Corporation
InventorsHan-Chang HO, Cheng-Hui LIN, Kuo-Ming HUANG, Kuo-Tai WANG
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Abstract
A capacitive touch pad includes a sensor layer for sensing a touch of an object and a dummy trace below the sensor layer. The dummy trace is sensed to obtain a sensed value while the dummy trace is shielded by the sensor layer from interference of the object such that the sensed value reflects only environmental variation. Therefore, environmental variation can be identified depending on the sensed value, and the sensor layer can be calibrated properly.
Claims11
A capacitive touch pad, comprising:
- a sensor layer operative to sense a touch of an object;
- and
- a dummy trace below the sensor layer;
- wherein the dummy trace is sensed to obtain a sensed value while the dummy trace is shielded by the sensor layer from interference of the object such that the sensed value reflects only environmental variation.
A method for eliminating environmental interference to a capacitive touch pad having a sensor layer for sensing a touch of an object and a dummy trace below the sensor layer, the method comprising steps of:
- sensing the dummy trace to obtain a sensed value while the dummy trace is shielded by the sensor layer from interference of the object such that the sensed value reflects only environmental variation;
- comparing a difference between the sensed value and a base value with a threshold value;
- and
- calibrating the sensor layer if the difference is greater than the threshold value.
Dependencies are inferred from the claim text.