Method of reducing computation of palm rejection by projecting touch data

Abstract

A method of reducing computation of palm rejection by projecting touch data is disclosed, targeting the handheld devices. The method targets first at obtaining a difference array, followed by extracting maximum values of rows and columns of the difference array to obtain a row projection list and a column projection list respectively. By repeated implementing of mutual capacitance detection, ghost palm blocks can be wiped out from the multiple palm blocks. Once integrating with a local spatial boundary detection algorithm, the sensed signals of intended input located within a rectangular palm block yet beyond a real palm block are consequently detected. The computational algorithm of the palm rejection of this invention is successfully built into the touch panel controller due to its substantially reduced computation.

Description

technical field [0001] The invention relates to a palm rejection method, in particular to a method for reducing palm rejection calculation by projecting touch data. Background technique [0002] Capacitive touch panels are mainly produced to improve the deterioration of resistive touch panels caused by scratches. Capacitive touch panels detect touches by identifying changes in an electrostatic field. Among all touch technologies, single-touch capacitive, which may also be called surface capacitive, is the most common and easy to manufacture. Compared with the single-point touch type, the projected capacitive type uses single-layer or multi-layer patterned indium tin oxide (ITO) to form a detection matrix. In the self-capacitance detection technology, this type of touch panel includes row electrodes 3 and column electrodes 4, such as Figure 1A and Figure 1B shown. Once a finger touches the touch panel, the self-capacitance of nearby electrodes will increase, which is th...

AI Technical Summary

Problems solved by technology

[0004] Although mutual capacitance is more suitable for multi-touch detection, the actual detection is more difficult than self-capacitance, and the capacitance change of mutual capacitance at each intersection is quite small

Assuming that mutual capacitance is the only applicable data, it usually cannot support advanced touch features, such as stylus detection

In addition, in the conventional technology, the amount of calculation for eliminating palm false touch is quite huge, so it cannot be built into the touch panel control chip

[0005] Therefore, from the capability and low efficiency of the conventional technology, it can be known that the self-capacitive type is limited to multi-touch detection, and the detection data of the mutual-capacitive type is smaller than that of the self-capacitive type.

Images