Patent ID: 8487893

Claim:
A capacitive touchscreen or touch panel system, comprising: a touchscreen comprising a first plurality of electrically conductive drive electrodes arranged in rows or columns, and a second plurality of electrically conductive sense electrodes arranged in rows or columns arranged at an angle with respect to the rows or columns of the first plurality of electrodes, mutual capacitances existing between the first and second pluralities of electrodes at locations where the first and second pluralities of electrodes intersect to form individual cells, the mutual capacitances changing in the presence of one or more fingers of a user or touch devices brought into proximity thereto; drive circuitry operably connected to the first plurality of drive electrodes; sense circuitry operably connected to the second plurality of sense electrodes and configured to sense input signals corresponding to the individual cells therefrom, and a controller operably connected to the first plurality of drive electrodes and the second plurality of sense electrodes, the controller comprising a central processing unit (CPU) and automatic level control (ALC) circuitry comprising: at least one scaler and decimator circuit configured to receive signals corresponding to the individual cells and to provide therefrom scaled and decimated output signals corresponding to such individual cells; a multiplier circuit operably connected to the scaler and decimator circuit and configured to receive the scaled and decimated output signals therefrom, and further to multiply such scaled and decimated output signals by a gain factor and to provide multiplier output signals therefrom; a first subtractor circuit operably connected to the multiplier circuit and configured to receive the multiplier output signals therefrom and to subtract a predetermined set point value from such multiplier output signals thereby to provide error output signals therefrom; an ALC control loop filter circuit operably connected to the CPU and the multiplier circuit and configured to calculate updated gain factors based on the error output signals and to provide such updated gain factors to the multiplier circuit, and a second subtractor circuit configured to subtract multiplied output signals from a desired set point value and to provide final output signals corresponding thereto to the CPU; wherein the CPU is configured to calculate touch position data based on the final output signals corresponding to the positions of the one or more fingers of the user or touch devices.