Pressure not consistent in relation to position on resistive touchpanel


After having worked a bit with a 8-inches 4-wire resistive touchpanel directly connected to an Arduino I have now inserted a TI's TSC2046 controller to improve the measurement quality.

However in both configurations the maximum pressure value changes a lot according to the position and makes this information unusable althought I have applied the calculations described in the IC's datasheets (and in many documents about 4-wire resistive touchpanels), using two cross panel measurements. In two corners I have values not greater than 15, in the third corner the value reaches 68 and in the fourth corner it goes beyond 100. In the center I have values beyond 100 also.

I am wondering if this problem comes from the size of the panel, the build quality from the specific panel I have of from the inherent principle of pressure measurement on 4-wire resistive panels.

I'd be interested to know if other people who measure a touchpanel's pressure information do have the same problem. Is it possible that some kind of decorrelation should be applied between measurements of the pressure and position ?

Thank you in advance.

Have you link to datasheets?

Touchpanel (PDF):

Controller :

Circuit : Box